Sat 06 Nov 2021
Tags: linux, sysadmin
GNU sort is an excellent
utility that is a mainstay of the linux command line. It has all kinds
of tricks up its sleeves, including support for uniquifying records,
stable sorts, files larger than memory, parallelisation, controlled
memory usage, etc. Go read the
man page
for all the gory details.
It also supports sorting with field separators, but unfortunately this
support has some nasty traps for the unwary. Hence this post.
First, GNU sort cannot do general sorts of CSV-style datasets, because
it doesn't understand CSV-features like quoting rules, quote-escaping,
separator-escaping, etc. If you have very simple CSV files that don't
do any escaping and you can avoid quotes altogether (or always use
them), you might be able to use GNU sort - but it can get difficult
fast.
Here I'm only interested in very simple delimited files - no quotes
or escaping at all, Even here, though, there are some nasty traps to
watch out for.
Here's a super-simple example file with just two lines and three fields,
called dsort.csv:
$ cat dsort.csv
a,b,c
a,b+c,c
If we do a vanilla sort on this file, we get the following (I'm also
running it through md5sum to highlight when the output changes):
$ sort dsort.csv | tee /dev/stderr | md5sum
a,b+c,c
a,b,c
5efd74fa9bef453dd477ec9acb2cef5f -
The longer line sorts before the shorter line because the '+' sign
collates before the second comma in the short line - this is sorting
on the whole line, not on the individual fields.
Okay, so if I want do an individual field sort, I can just use the -t
option, right? You would think so, but unfortunately:
$ sort -t, dsort.csv | tee /dev/stderr | md5sum
a,b+c,c
a,b,c
5efd74fa9bef453dd477ec9acb2cef5f -
Huh? Why doesn't that work the short line first, like we'd expect?
Maybe it's not sorting on all the fields or something? Do I need to
explicitly include all fields? Let's see:
$ sort -t, -k1,3 dsort.csv | tee /dev/stderr | md5sum
a,b+c,c
a,b,c
5efd74fa9bef453dd477ec9acb2cef5f -
Huh? What the heck is going on here?
It turns out this unintuitive behaviour is because of the way sort
interprets the the -k option - -kM,N (where M != N) doesn't mean
'sort by field M, then field M+1,... then by field N', it means instead
'join all fields from M to N (with the field separator?), and sort by
that'. Ugh!
So I just need to specify the fields individually? Unfortunately, even
that's not enough:
$ sort -t, -k1 -k2 -k3 dsort.csv | tee /dev/stderr | md5sum
a,b+c,c
a,b,c
5efd74fa9bef453dd477ec9acb2cef5f -
This is because the first option here - -k1 is interpreted as -k1,3
(since the last field is '3'), because the default 'end-field' is the
last. Double-ugh!
So the takeaway is: if you want an individual-field sort you have to
specify every field individually, AND you have to use -kN,N syntax,
like so:
$ sort -t, -k1,1 -k2,2 -k3,3 dsort.csv | tee /dev/stderr | md5sum
a,b,c
a,b+c,c
493ce7ca60040fa184f1bf7db7758516 -
Yay, finally what we're after!
Also, unfortunately, there doesn't seem to be a generic way of
specifying 'all fields' or 'up to the last field' or 'M-N' fields -
you have to specify them all individually. It's verbose and ugly, but
it works.
And for some good news, you can use sort suffixes on those individual
options (like n for numerics, r for reverse sorts, etc.) just fine.
Happy sorting!
Sun 05 May 2019
Tags: linux, centos, networking
Recently had to setup a few servers that needed dual upstream gateways,
and used an ancient blog post
I wrote 11 years ago (!) to get it all working. This time around I hit a
gotcha that I hadn't noted in that post, and used a simpler method to
define the rules, so this is an updated version of that post.
Situation: you have two upstream gateways (gw1 and gw2) on separate
interfaces and subnets on your linux server. Your default route is via gw1
(so all outward traffic, and most incoming traffic goes via that), but you
want to be able to use gw2 as an alternative ingress pathway, so that
packets that have come in on gw2 go back out that interface.
(Everything below done as root, so sudo -i first if you need to.)
1) First, define a few variables to make things easier to modify/understand:
# The device/interface on the `gw2` subnet
GW2_DEV=eth1
# The ip address of our `gw2` router
GW2_ROUTER_ADDR=172.16.2.254
# Our local ip address on the `gw2` subnet i.e. $GW2_DEV's address
GW2_LOCAL_ADDR=172.16.2.10
2) The gotcha I hit was that 'strict reverse-path filtering' in the kernel
will drop all asymmetrically routed entirely, which will kill our response
traffic. So the first thing to do is make sure that is either turned off
or set to 'loose' instead of 'strict':
# Check the rp_filter setting for $GW2_DEV
# A value of '0' means rp_filtering is off, '1' means 'strict', and '2' means 'loose'
$ cat /proc/sys/net/ipv4/conf/$GW2_DEV/rp_filter
1
# For our purposes values of either '0' or '2' will work. '2' is slightly
# more conservative, so we'll go with that.
echo 2 > /proc/sys/net/ipv4/conf/$GW2_DEV/rp_filter
$ cat /proc/sys/net/ipv4/conf/$GW2_DEV/rp_filter
2
3) Define an extra routing table called gw2 e.g.
$ cat /etc/iproute2/rt_tables
#
# reserved values
#
255 local
254 main
253 default
0 unspec
#
# local tables
#
102 gw2
#
4) Add a default route via gw2 (here 172.16.2.254) to the gw2 routing table:
$ echo "default table gw2 via $GW2_ROUTER_ADDR" > /etc/sysconfig/network-scripts/route-${GW2_DEV}
$ cat /etc/sysconfig/network-scripts/route-${GW2_DEV}
default table gw2 via 172.16.2.254
5) Add an iproute 'rule' saying that packets that come in on our $GW2_LOCAL_ADDR
should use routing table gw2:
$ echo "from $GW2_LOCAL_ADDR table gw2" > /etc/sysconfig/network-scripts/rule-${GW2_DEV}
$ cat /etc/sysconfig/network-scripts/rule-${GW2_DEV}
from 172.16.2.10 table gw2
6) Take $GW2_DEV down and back up again, and test:
$ ifdown $GW2_DEV
$ ifup $GW2_DEV
# Test that incoming traffic works as expected e.g. on an external server
$ ssh -v server-via-gw2
For more, see:
Fri 31 Aug 2018
Tags: linux, sysadmin
(Updated April 2020: added new no. 7 after being newly bitten...)
incron
is a useful little cron-like utility that lets you run arbitrary jobs
(like cron), but instead of being triggered at certain times, your
jobs are triggered by changes to files or directories.
It uses the linux kernel inotify
facility (hence the name), and so it isn't cross-platform, but on linux
it can be really useful for monitoring file changes or uploads, reporting
or forwarding based on status files, simple synchronisation schemes, etc.
Again like cron, incron supports the notion of job 'tables' where
commands are configured, and users can have manage their own tables
using an incrontab command, while root can manage multiple system
tables.
So it's a really useful linux utility, but it's also fairly old (the
last release, v0.5.10, is from 2012), doesn't appear to be under
active development any more, and it has a few frustrating quirks that
can make using it unnecessarily difficult.
So this post is intended to highlight a few of the 'gotchas' I've
experienced using incron:
You can't monitor recursively i.e. if you create a watch on a
directory incron will only be triggered on events in that
directory itself, not in any subdirectories below it. This isn't
really an incron issue since it's a limitation of the underlying
inotify mechanism, but it's definitely something you'll want
to be aware of going in.
The incron interface is enough like cron (incrontab -l,
incrontab -e, man 5 incrontab, etc.) that you might think
that all your nice crontab features are available. Unfortunately
that's not the case - most significantly, you can't have comments
in incron tables (incron will try and parse your comment lines and
fail), and you can't set environment variables to be available for
your commands. (This includes PATH, so you might need to explicitly
set a PATH inside your incron scripts if you need non-standard
locations. The default PATH is documented as
/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin.)
That means that cron MAILTO support is not available, and in
general there's no easy way of getting access to the stdout or
stderr of your jobs. You can't even use shell redirects in your
command to capture the output (e.g. echo $@/$# >> /tmp/incron.log
doesn't work). If you're debugging, the best you can do is add a
layer of indirection by using a wrapper script that does the
redirection you need (e.g. echo $1 2&>1 >> /tmp/incron.log)
and calling the wrapper script in your incrontab with the incron
arguments (e.g. debug.sh $@/$#). This all makes debugging
misbehaving commands pretty painful. The main place to check if
your commands are running is the cron log (/var/log/cron) on
RHEL/CentOS, and syslog (/var/log/syslog) on Ubuntu/Debian.
incron is also very picky about whitespace in your incrontab.
If you put more than one space (or a tab) between the inotify
masks and your command, you'll get an error in your cron log
saying cannot exec process: No such file or directory, because
incron will have included everything after the first space as part
of your command e.g. (gavin) CMD ( echo /home/gavin/tmp/foo)
(note the evil space before the echo).
It's often difficult (and non-intuitive) to figure out what inotify
events you want to trigger on in your incrontab masks. For instance,
does 'IN_CREATE' get fired when you replace an existing file with a
new version? What events are fired when you do a mv or a cp?
If you're wanting to trigger on an incoming remote file copy, should
you use 'IN_CREATE' or 'IN_CLOSE_WRITE'? In general, you don't want to guess,
you actually want to test and see what events actually get fired on
the operations you're interested in. The easiest way to do this is
use inotifywait from the inotify-tools package, and run it using
inotifywait -m <dir>, which will report to you all the inotify
events that get triggered on that directory (hit <Ctrl-C> to exit).
The "If you're wanting to trigger on an incoming remote file copy,
should you use 'IN_CREATE' or 'IN_CLOSE_WRITE'?" above was a trick
question - it turns out it depends how you're doing the copy! If
you're just going a simple copy in-place (e.g. with scp), then
(assuming you want the completed file) you're going to want to trigger
on 'IN_CLOSE_WRITE', since that's signalling all writing is complete and
the full file will be available. If you're using a vanilla rsync,
though, that's not going to work, as rsync does a clever
write-to-a-hidden-file trick, and then moves the hidden file to
the destination name atomically. So in that case you're going to want
to trigger on 'IN_MOVED_TO', which will give you the destination
filename once the rsync is completed. So again, make sure you test
thoroughly before you deploy.
Though cron works fine with symlinks to crontab files (in e.g.
/etc/cron.d, incron doesn't support this in /etc/incron.d -
symlinks just seem to be quietly ignored. (Maybe this is for
security, but it's not documented, afaict.)
Have I missed any? Any other nasties bitten you using incron?
Mon 27 Nov 2017
Tags: linux, mdadm, lvm
Ran out of space on an old CentOS 6.8 server in the weekend, and so had
to upgrade the main data mirror from a pair of Hitachi 2TB HDDs to a pair
of 4TB WD Reds I had lying around.
The volume was using mdadm, aka Linux Software RAID, and is a simple mirror
(RAID1), with LVM volumes on top of the mirror. The safest upgrade path is
to build a new mirror on the new disks and sync the data across, but there
weren't any free SATA ports on the motherboard, so instead I opted to do an
in-place upgrade. I haven't done this for a good few years, and hit a couple
of wrinkles on the way, so here are the notes from the journey.
Below, the physical disk partitions are /dev/sdb1 and /dev/sdd1, the
mirror is /dev/md1, and the LVM volume group is extra.
1. Backup your data (or check you have known good rock-solid backups in
place), because this is a complex process with plenty that could go wrong.
You want an exit strategy.
2. Break the mirror, failing and removing one of the old disks
mdadm --manage /dev/md1 --fail /dev/sdb1
mdadm --manage /dev/md1 --remove /dev/sdb1
3. Shutdown the server, remove the disk you've just failed, and insert your
replacement. Boot up again.
4. Since these are brand new disks, we need to partition them. And since
these are 4TB disks, we need to use parted rather than the older fdisk.
parted /dev/sdb
print
mklabel gl
# Create a partition, skipping the 1st MB at beginning and end
mkpart primary 1 -1
unit s
print
# Not sure if this flag is required, but whatever
set 1 raid on
quit
5. Then add the new partition back into the mirror. Although this is much
bigger, it will just sync up at the old size, which is what we want for now.
mdadm --manage /dev/md1 --add /dev/sdb1
# This will take a few hours to resync, so let's keep an eye on progress
watch -n5 cat /proc/mdstat
6. Once all resynched, rinse and repeat with the other disk - fail and remove
/dev/sdd1, shutdown and swap the new disk in, boot up again, partition the new
disk, and add the new partition into the mirror.
7. Once all resynched again, you'll be back where you started - a nice stable
mirror of your original size, but with shiny new hardware underneath. Now we
can grow the mirror to take advantage of all this new space we've got.
mdadm --grow /dev/md1 --size=max
mdadm: component size of /dev/md0 has been set to 2147479552K
Ooops! That size doesn't look right, that's 2TB, but these are 4TB disks?!
Turns out there's a 2TB limit on mdadm metadata version 0.90, which this
mirror is using, as documented on https://raid.wiki.kernel.org/index.php/RAID_superblock_formats#The_version-0.90_Superblock_Format.
mdadm --detail /dev/md1
/dev/md1:
Version : 0.90
Creation Time : Thu Aug 26 21:03:47 2010
Raid Level : raid1
Array Size : 2147483648 (2048.00 GiB 2199.02 GB)
Used Dev Size : -1
Raid Devices : 2
Total Devices : 2
Preferred Minor : 1
Persistence : Superblock is persistent
Update Time : Mon Nov 27 11:49:44 2017
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
UUID : f76c75fb:7506bc25:dab805d9:e8e5d879
Events : 0.1438
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 49 1 active sync /dev/sdd1
Unfortunately, mdadm doesn't support upgrading the metadata version. But
there is a workaround documented on that wiki page, so let's try that:
mdadm --detail /dev/md1
# (as above)
# Stop/remove the mirror
mdadm --stop /dev/md1
mdadm: Cannot get exclusive access to /dev/md1:Perhaps a running process, mounted filesystem or active volume group?
# Okay, deactivate our volume group first
vgchange --activate n extra
# Retry stop
mdadm --stop /dev/md1
mdadm: stopped /dev/md1
# Recreate the mirror with 1.0 metadata (you can't go to 1.1 or 1.2, because they're located differently)
# Note that you should specify all your parameters in case the defaults have changed
mdadm --create /dev/md1 -l1 -n2 --metadata=1.0 --assume-clean --size=2147483648 /dev/sdb1 /dev/sdd1
That outputs:
mdadm: /dev/sdb1 appears to be part of a raid array:
level=raid1 devices=2 ctime=Thu Aug 26 21:03:47 2010
mdadm: /dev/sdd1 appears to be part of a raid array:
level=raid1 devices=2 ctime=Thu Aug 26 21:03:47 2010
mdadm: largest drive (/dev/sdb1) exceeds size (2147483648K) by more than 1%
Continue creating array? y
mdadm: array /dev/md1 started.
Success! Now let's reactivate that volume group again:
vgchange --activate y extra
3 logical volume(s) in volume group "extra" now active
Another wrinkle is that recreating the mirror will have changed the array UUID,
so we need to update the old UUID in /etc/mdadm.conf:
# Double-check metadata version, and record volume UUID
mdadm --detail /dev/md1
# Update the /dev/md1 entry UUID in /etc/mdadm.conf
$EDITOR /etc/mdadm.conf
So now, let's try that mdadm --grow command again:
mdadm --grow /dev/md1 --size=max
mdadm: component size of /dev/md1 has been set to 3907016564K
# Much better! This will take a while to synch up again now:
watch -n5 cat /proc/mdstat
8. (You can wait for this to finish resynching first, but it's optional.)
Now we need to let LVM know that the physical volume underneath it has changed size:
# Check our starting point
pvdisplay /dev/mda1
--- Physical volume ---
PV Name /dev/md1
VG Name extra
PV Size 1.82 TiB / not usable 14.50 MiB
Allocatable yes
PE Size 64.00 MiB
Total PE 29808
Free PE 1072
Allocated PE 28736
PV UUID mzLeMW-USCr-WmkC-552k-FqNk-96N0-bPh8ip
# Resize the LVM physical volume
pvresize /dev/md1
Read-only locking type set. Write locks are prohibited.
Can't get lock for system
Cannot process volume group system
Read-only locking type set. Write locks are prohibited.
Can't get lock for extra
Cannot process volume group extra
Read-only locking type set. Write locks are prohibited.
Can't get lock for #orphans_lvm1
Cannot process standalone physical volumes
Read-only locking type set. Write locks are prohibited.
Can't get lock for #orphans_pool
Cannot process standalone physical volumes
Read-only locking type set. Write locks are prohibited.
Can't get lock for #orphans_lvm2
Cannot process standalone physical volumes
Read-only locking type set. Write locks are prohibited.
Can't get lock for system
Cannot process volume group system
Read-only locking type set. Write locks are prohibited.
Can't get lock for extra
Cannot process volume group extra
Read-only locking type set. Write locks are prohibited.
Can't get lock for #orphans_lvm1
Cannot process standalone physical volumes
Read-only locking type set. Write locks are prohibited.
Can't get lock for #orphans_pool
Cannot process standalone physical volumes
Read-only locking type set. Write locks are prohibited.
Can't get lock for #orphans_lvm2
Cannot process standalone physical volumes
Failed to find physical volume "/dev/md1".
0 physical volume(s) resized / 0 physical volume(s) not resized
Oops - that doesn't look good. But it turns out it's just a weird
locking type default. If we tell pvresize it can use local filesystem
write locks we should be good (cf. /etc/lvm/lvm.conf):
# Let's try that again...
pvresize --config 'global {locking_type=1}' /dev/md1
Physical volume "/dev/md1" changed
1 physical volume(s) resized / 0 physical volume(s) not resized
# Double-check the PV Size
pvdisplay /dev/mda1
--- Physical volume ---
PV Name /dev/md1
VG Name extra
PV Size 3.64 TiB / not usable 21.68 MiB
Allocatable yes
PE Size 64.00 MiB
Total PE 59616
Free PE 30880
Allocated PE 28736
PV UUID mzLeMW-USCr-WmkC-552k-FqNk-96N0-bPh8ip
Success!
Finally, you can now resize your logical volumes using lvresize as you
usually would.
Fri 08 Jul 2016
Tags: linux, sysadmin
Since I got bitten by this recently, let me blog a quick warning here:
glibc iconv - a utility for character set conversions, like iso8859-1 or
windows-1252 to utf-8 - has a nasty misfeature/bug: if you give it data on
stdin it will slurp the entire file into memory before it does a single
character conversion.
Which is fine if you're running small input files. If you're trying to
convert a 10G file on a VPS with 2G of RAM, however ... not so good!
This looks to be a
known issue, with
patches submitted to fix it in August 2015, but I'm not sure if they've
been merged, or into which version of glibc. Certainly RHEL/CentOS 7 (with
glibc 2.17) and Ubuntu 14.04 (with glibc 2.19) are both affected.
Once you know about the issue, it's easy enough to workaround - there's an
iconv-chunks wrapper on github that
breaks the input into chunks before feeding it to iconv, or you can do much
the same thing using the lovely GNU parallel
e.g.
gunzip -c monster.csv.gz | parallel --pipe -k iconv -f windows-1252 -t utf8
Nasty OOM avoided!
Tue 06 Oct 2015
Tags: hardware, linux, rhel, centos
Wow, almost a year since the last post. Definitely time to reboot the blog.
Got to replace my aging ThinkPad X201 with a lovely shiny new
ThinkPad X250
over the weekend. Specs are:
- CPU: Intel(R) Core(TM) i5-5300U CPU @ 2.30GHz
- RAM: 16GB PC3-12800 DDR3L SDRAM 1600MHz SODIMM
- Disk: 256GB SSD (swapped out for existing Samsung SSD)
- Display: 12.5" 1920x1080 IPS display, 400nit, non-touch
- Graphics: Intel Graphics 5500
- Wireless: Intel 7265 AC/B/G/N Dual Band Wireless and Bluetooth 4.0
- Batteries: 1 3-cell internal, 1 6-cell hot-swappable
A very nice piece of kit!
Just wanted to document what works and what doesn't (so far) on my standard OS,
CentOS 7, with RH kernel 3.10.0-229.11.1. I had to install the following
additional packages:
- iwl7265-firmware (for wireless support)
- acpid (for the media buttons)
Working so far:
- media buttons (Fn + F1/mute, F2/softer, F3/louder - see below for configuration)
- wifi button (Fn + F8 - worked out of the box)
- keyboard backlight (Fn + space, out of the box)
- sleep/resume (out of the box)
- touchpad hard buttons (see below)
- touchpad soft buttons (out of the box)
Not working / unconfigured so far:
- brightness buttons (Fn + F5/F6)
- fingerprint reader (supposedly works with
fprintd)
Not working / no ACPI codes:
- mute microphone button (Fn + F4)
- application buttons (Fn + F9-F12)
Uncertain/not tested yet:
- switch video mode (Fn + F7)
To get the touchpad working I needed to use the "evdev" driver rather than the
"Synaptics" one - I added the following as /etc/X11/xorg.conf.d/90-evdev.conf:
Section "InputClass"
Identifier "Touchpad/TrackPoint"
MatchProduct "PS/2 Synaptics TouchPad"
MatchDriver "evdev"
Option "EmulateWheel" "1"
Option "EmulateWheelButton" "2"
Option "Emulate3Buttons" "0"
Option "XAxisMapping" "6 7"
Option "YAxisMapping" "4 5"
EndSection
This gives me 3 working hard buttons above the touchpad, including middle-mouse-
button for paste.
To get fonts scaling properly I needed to add a monitor section as
/etc/X11/xorg.conf.d/50-monitor.conf, specifically for the DisplaySize:
Section "Monitor"
Identifier "Monitor0"
VendorName "Lenovo ThinkPad"
ModelName "X250"
DisplaySize 276 155
Option "DPMS"
EndSection
and also set the dpi properly in my ~/.Xdefaults:
*.dpi: 177
This fixes font size nicely in Firefox/Chrome and terminals for me.
I also found my mouse movement was too slow, which I fixed with:
xinput set-prop 11 "Device Accel Constant Deceleration" 0.7
(which I put in my old-school ~/.xsession file).
Finally, getting the media keys involved installing acpid and setting up
the appropriate magic in 3 files in /etc/acpid/events:
# /etc/acpi/events/volumedown
event=button/volumedown
action=/etc/acpi/actions/volume.sh down
# /etc/acpi/events/volumeup
event=button/volumeup
action=/etc/acpi/actions/volume.sh up
# /etc/acpi/events/volumemute
event=button/mute
action=/etc/acpi/actions/volume.sh mute
Those files capture the ACPI events and handle them via a custom script in
/etc/acpi/actions/volume.sh, which uses amixer from alsa-utils. Volume
control worked just fine, but muting was a real pain to get working correctly
due to what seems like a bug in amixer - amixer -c1 sset Master playback toggle
doesn't toggle correctly - it mutes fine, but then doesn't unmute all
the channels it mutes!
I worked around it by figuring out the specific channels that sset Master
was muting, and then handling them individually, but it's definitely not as clean:
#!/bin/sh
#
# /etc/acpi/actions/volume.sh (must be executable)
#
PATH=/usr/bin
die() {
echo $*
exit 1
}
usage() {
die "usage: $(basename $0) up|down|mute"
}
test -n "$1" || usage
ACTION=$1
shift
case $ACTION in
up)
amixer -q -c1 -M sset Master 5%+ unmute
;;
down)
amixer -q -c1 -M sset Master 5%- unmute
;;
mute)
# Ideally the next command should work, but it doesn't unmute correctly
# amixer -q -c1 sset Master playback toggle
# Manual version for ThinkPad X250 channels
# If adapting for another machine, 'amixer -C$DEV contents' is your friend (NOT 'scontents'!)
SOUND_IS_OFF=$(amixer -c1 cget iface=MIXER,name='Master Playback Switch' | grep 'values=off')
if [ -n "$SOUND_IS_OFF" ]; then
amixer -q -c1 cset iface=MIXER,name='Master Playback Switch' on
amixer -q -c1 cset iface=MIXER,name='Headphone Playback Switch' on
amixer -q -c1 cset iface=MIXER,name='Speaker Playback Switch' on
else
amixer -q -c1 cset iface=MIXER,name='Master Playback Switch' off
amixer -q -c1 cset iface=MIXER,name='Headphone Playback Switch' off
amixer -q -c1 cset iface=MIXER,name='Speaker Playback Switch' off
fi
;;
*)
usage
;;
esac
So in short, really pleased with the X250 so far - the screen is lovely, battery
life seems great, I'm enjoying the keyboard, and most things have Just
Worked or have been pretty easily configurable with CentOS. Happy camper!
References:
Sun 21 Sep 2014
Tags: hardware, linux, scanning, rhel, centos, usb
Just picked up a shiny new Fujitsu ScanSnap 1300i ADF scanner to get
more serious about less paper.
I chose the 1300i on the basis of the nice small form factor, and that SANE
reports
it having 'good' support with current SANE backends. I'd also been able
to find success stories of other linux users getting the similar S1300
working okay:
Here's my experience getting the S1300i up and running on CentOS 6.
I had the following packages already installed on my CentOS 6
workstation, so I didn't need to install any new software:
- sane-backends
- sane-backends-libs
- sane-frontends
- xsane
- gscan2pdf (from rpmforge)
- gocr (from rpmforge)
- tesseract (from my repo)
I plugged the S1300i in (via the dual USB cables instead of the power
supply - nice!), turned it on (by opening the top cover) and then ran
sudo sane-find-scanner. All good:
found USB scanner (vendor=0x04c5 [FUJITSU], product=0x128d [ScanSnap S1300i]) at libusb:001:013
# Your USB scanner was (probably) detected. It may or may not be supported by
# SANE. Try scanimage -L and read the backend's manpage.
Ran sudo scanimage -L - no scanner found.
I downloaded the S1300 firmware Luuk had provided in his post and
installed it into /usr/share/sane/epjitsu, and then updated
/etc/sane.d/epjitsu.conf to reference it:
# Fujitsu S1300i
firmware /usr/share/sane/epjitsu/1300_0C26.nal
usb 0x04c5 0x128d
Ran sudo scanimage -L - still no scanner found. Hmmm.
Rebooted into windows, downloaded the Fujitsu ScanSnap Manager package
and installed it. Grubbed around in C:/Windows and found the following 4
firmware packages:
Copied the firmware onto another box, and rebooted back into linux.
Copied the 4 new firmware files into /usr/share/sane/epjitsu and
updated /etc/sane.d/epjitsu.conf to try the 1300i firmware:
# Fujitsu S1300i
firmware /usr/share/sane/epjitsu/1300i_0D12.nal
usb 0x04c5 0x128d
Close and re-open the S1300i (i.e. restart, just to be sure), and
retried sudo scanimage -L. And lo, this time the scanner whirrs
briefly and ... victory!
$ sudo scanimage -L
device 'epjitsu:libusb:001:014' is a FUJITSU ScanSnap S1300i scanner
I start gscan2pdf to try some scanning goodness. Eeerk: "No devices
found". Hmmm. How about sudo gscan2pdf? Ahah, success - "FUJITSU
ScanSnap S1300i" shows up in the Device dropdown.
I exit, and google how to deal with the permissions problem. Looks like
the usb device gets created by udev as root:root 0664, and I need 'rw'
permissions for scanning:
$ ls -l /dev/bus/usb/001/014
crw-rw-r--. 1 root root 189, 13 Sep 20 20:50 /dev/bus/usb/001/014
The fix is to add a scanner group and local udev rule to use that
group when creating the device path:
# Add a scanner group (analagous to the existing lp, cdrom, tape, dialout groups)
$ sudo groupadd -r scanner
# Add myself to the scanner group
$ sudo useradd -aG scanner gavin
# Add a udev local rule for the S1300i
$ sudo vim /etc/udev/rules.d/99-local.rules
# Added:
# Fujitsu ScanSnap S1300i
ATTRS{idVendor}=="04c5", ATTRS{idProduct}=="128d", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"
Then logout and log back in to pickup the change in groups, and close
and re-open the S1300i. If all is well, I'm now in the scanner group and
can control the scanner sans sudo:
# Check I'm in the scanner group now
$ id
uid=900(gavin) gid=100(users) groups=100(users),10(wheel),487(scanner)
# Check I can scanimage without sudo
$ scanimage -L
device 'epjitsu:libusb:001:016' is a FUJITSU ScanSnap S1300i scanner
# Confirm the permissions on the udev path (adjusted to match the new libusb path)
$ ls -l /dev/bus/usb/001/016
crw-rw-r--. 1 root scanner 189, 15 Sep 20 21:30 /dev/bus/usb/001/016
# Success!
Try gscan2pdf again, and this time it works fine without sudo!
And so far gscan2pdf 1.2.5 seems to work pretty nicely. It handles both
simplex and duplex scans, and both the cleanup phase (using unpaper)
and the OCR phase (with either gocr or tesseract) work without
problems. tesseract seems to perform markedly better than gocr so
far, as seems pretty typical.
So thus far I'm a pretty happy purchaser. On to a paperless
searchable future!
Mon 20 May 2013
Tags: dell, drac, linux, sysadmin
Note to self: this seems to be the most reliable way of checking whether
a Dell machine has a DRAC card installed:
sudo ipmitool sdr elist mcloc
If there is, you'll see some kind of DRAC card:
iDRAC6 | 00h | ok | 7.1 | Dynamic MC @ 20h
If there isn't, you'll see only a base management controller:
BMC | 00h | ok | 7.1 | Dynamic MC @ 20h
You need ipmi setup for this (if you haven't already):
# on RHEL/CentOS etc.
yum install OpenIPMI
service ipmi start
Tue 08 May 2012
Tags: centos, rhel, yum
Ok, this has bitten me enough times now that I'm going to blog it so I
don't forget it again.
Symptom: you're doing a yum update on a centos5 or rhel5 box, using rpms
from a repository on a centos6 or rhel6 server (or anywhere else with
a more modern createrepo available), and you get errors like this:
http://example.com/repodata/filelists.sqlite.bz2: [Errno -3] Error performing checksum
http://example.com/repodata/primary.sqlite.bz2: [Errno -3] Error performing checksum
What this really means that yum is too stupid to calculate the sha256
checksum correctly (and also too stupid to give you a sensible error
message like "Sorry, primary.sqlite.bz2 is using a sha256 checksum,
but I don't know how to calculate that").
The fix is simple:
yum install python-hashlib
from either rpmforge or epel, which makes the necessary libraries
available for yum to calculate the new checksums correctly. Sorted.
Tue 13 Mar 2012
I've been enjoying playing around with ZeroMQ
lately, and exploring some of the ways it changes the way you approach
system architecture.
One of the revelations for me has been how powerful the pub-sub (Publish-
Subscribe) pattern is. An architecture that makes it straightforward for
multiple consumers to process a given piece of data promotes lots of
small simple consumers, each performing a single task, instead of a
complex monolithic processor.
This is both simpler and more complex, since you end up with more
pieces, but each piece is radically simpler. It's also more flexible and
more scalable, since you can move components around individually, and it
allows greater language and library flexibility, since you can write
individual components in completely different languages.
What's also interesting is that the benefits of this pattern don't
necessarily require an advanced toolkit like ZeroMQ, particularly for
low-volume applications. Here's a sketch of a low-tech pub-sub pattern
that uses files as the pub-sub inflection point, and
incron, the 'inotify cron' daemon, as our
dispatcher.
Recipe:
Install incron, the inotify cron daemon, to monitor our data directory
for changes. On RHEL/CentOS this is available from the rpmforge or EPEL
repositories: yum install incron.
Capture data to files in our data directory in some useful format
e.g. json, yaml, text, whatever.
Setup an incrontab entry for each consumer monitoring CREATE operations
on our data directory e.g.
/data/directory IN_CREATE /path/to/consumer1 $@/$#
/data/directory IN_CREATE /path/to/consumer2 $@/$#
/data/directory IN_CREATE /path/to/consumer3 $@/$#
The $@/$# magic passes the full file path to your consumer - see man 5
incrontab for details and further options.
Done. Working pub-sub with minimal moving parts.
Fri 13 Jan 2012
Tags: aoe, coraid, centos, rhel
Updated 2012-07-24: packages updated to aoe-80 and aoetools-34,
respectively.
I'm a big fan of Coraid and their relatively
low-cost storage units.
I've been using them for 5+ years now, and they've always been pretty
well engineered, reliable, and performant.
They talk ATA-over-Ethernet (AoE),
which is a very simple non-routable protocol for transmitting ATA
commands directly via Ethernet frames, without the overhead of higher
level layers like IP and TCP. So they're a lighter protocol than
something like iSCSI, and so theoretically higher performance.
One issue with them on linux is that the in-kernel 'aoe' driver is
typically pretty old. Coraid's
latest aoe driver is version
78, for instance, while the RHEL6 kernel (2.6.32) comes with aoe v47,
and the RHEL5 kernel (2.6.18) comes with aoe v22. So updating to the
latest version is highly recommended, but also a bit of a pain, because
if you do it manually it has to be recompiled for each new kernel
update.
The modern way to handle this is to use a
kernel-ABI tracking kmod, which gives you
a driver that will work across multiple kernel updates for a given EL
generation, without having to recompile each time.
So I've created a kmod-aoe package that seems to work nicely here. It's
downloadable below, or you can install it from my
yum repository.
The kmod depends on the 'aoetools' package, which supplies the command
line utilities for managing your AoE devices.
kmod-aoe (v80):
aoetools (v34):
There's an init script in the aoetools package that loads the kernel module,
activates any configured LVM volume groups, and mounts any filesystems.
All configuration is done via /etc/sysconfig/aoe.
Fri 28 Oct 2011
Tags: ldap, openldap, rhel, centos, linux, sysadmin
Having spent too much of this week debugging problems around migrating
ldap servers from RHEL5 to RHEL6, here are some miscellaneous notes
to self:
The service is named ldap on RHEL5, and slapd on RHEL6 e.g.
you do service ldap start on RHEL5, but service slapd start
on RHEL6
On RHEL6, you want all of the following packages installed on your clients:
yum install openldap-clients pam_ldap nss-pam-ldapd
This seems to be the magic incantation that works for me (with real SSL
certificates, though):
authconfig --enableldap --enableldapauth \
--ldapserver ldap.example.com \
--ldapbasedn="dc=example,dc=com" \
--update
Be aware that there are multiple ldap configuration files involved now.
All of the following end up with ldap config entries in them and need to
be checked:
- /etc/openldap/ldap.conf
- /etc/pam_ldap.conf
- /etc/nslcd.conf
- /etc/sssd/sssd.conf
Note too that /etc/openldap/ldap.conf uses uppercased directives (e.g. URI)
that get lowercased in the other files (URI -> uri). Additionally, some
directives are confusingly renamed as well - e.g. TLA_CACERT in
/etc/openldap/ldap.conf becomes tla_cacertfile in most of the others.
:-(
If you want to do SSL or TLS, you should know that the default behaviour
is for ldap clients to verify certificates, and give misleading bind errors
if they can't validate them. This means:
if you're using self-signed certificates, add TLS_REQCERT allow to
/etc/openldap/ldap.conf on your clients, which means allow certificates
the clients can't validate
if you're using CA-signed certificates, and want to verify them, add
your CA PEM certificate to a directory of your choice (e.g.
/etc/openldap/certs, or /etc/pki/tls/certs, for instance), and point
to it using TLA_CACERT in /etc/openldap/ldap.conf, and
tla_cacertfile in /etc/ldap.conf.
RHEL6 uses a new-fangled /etc/openldap/slapd.d directory for the old
/etc/openldap/slapd.conf config data, and the
RHEL6 Migration Guide
tells you to how to convert from one to the other. But if you simply
rename the default slapd.d directory, slapd will use the old-style
slapd.conf file quite happily, which is much easier to read/modify/debug,
at least while you're getting things working.
If you run into problems on the server, there are lots of helpful utilities
included with the openldap-servers package. Check out the manpages for
slaptest(8), slapcat(8), slapacl(8), slapadd(8), etc.
Further reading:
Tue 18 Oct 2011
Tags: linux, sysadmin, centos, rhel
rpm-find-changes is a little script I wrote a while ago for rpm-based
systems (RedHat, CentOS, Mandriva, etc.). It finds files in a filesystem
tree that are not owned by any rpm package (orphans), or are modified
from the version distributed with their rpm. In other words, any file
that has been introduced or changed from it's distributed version.
It's intended to help identify candidates for backup, or just for
tracking interesting changes. I run it nightly on /etc on most of my
machines, producing a list of files that I copy off the machine (using
another tool, which I'll blog about later) and store in a git
repository.
I've also used it for tracking changes to critical configuration trees
across multiple machines, to make sure everything is kept in sync, and
to be able to track changes over time.
Available on github:
https://github.com/gavincarr/rpm-find-changes
Mon 08 Aug 2011
Tags: googleplus, hangout, centos
Kudos to Google for providing linux plugins for their
Google Plus+
Hangouts (a multi-way video chat system), for both debian-based and
rpm-based systems. The library requirements don't seem to be
documented anywhere though, so here's the magic incantation required
for installation on CentOS6 x86_64:
yum install libstdc++.i686 gtk2.i686 \
libXrandr.i686 libXcomposite.i686 libXfixes.i686 \
pulseaudio-libs.i686 alsa-lib.i686
Wed 29 Jun 2011
Tags: date, hacks, ntp
One of today's annoyances was a third-party complaining about clock
skew on a server at their site that they're testing against. No, they
don't have a local ntp server, and no, they couldn't allow us to
connect out to a designated ntp server externally. All we have is an
ssh forward in.
They wanted me to manually set the clock on the server whenever they
noticed it was out of synch! Real professionals.
I thought about tunneling an ntp stream out, but that requires
udp-to-tcp fudging at each end, or using ssh's Tunnel facility, which
requires root at both ends.
In the end, I settled for the low-tech approach - a once a day cron
job that resets the time based on a local clock. Ugly, but good enough:
ssh root@server date --utc $(date --utc "+%m%d%H%M%Y.%S")
Fri 14 Jan 2011
Tags: linux, rhel6, centos6, gdm
Update: ilaiho has provided a better solution in the comments,
which is to install the xorg-x11-xinit-session package, which adds
a "User script" session option. This will invoke your (executable)
~/.xsession or ~/.Xclients configs, if selected, and works well,
so I'd recommend you go that route instead of using this patch now.
The GDM Greeter in RHEL6 seems to have lost the ability to select
'session types' (or window managers), which apparently means you're
stuck using Gnome, even if you have other better options installed.
One workaround is to install KDM instead, and set DISPLAYMANAGER=KDE
in your /etc/sysconfig/desktop config, as KDM does still support
selectable session types.
Since I've become a big fan of
tiling window managers
in general, and ion
in particular, this was pretty annoying, so I wasted a few hours
today working through the /etc/X11 scripts and figuring out how
they hung together on RHEL6.
So for any other gnome-haters out there who don't want to have to
go to KDM, here's a patch to /etc/X11/xinit/Xsession that ignores
the default 'gnome-session' set by GDM, which allows proper window
manager selection either by user .xsession or .Xclients files,
or by the /etc/sysconfig/desktop DISPLAY setting.
diff --git a/xinit/Xsession b/xinit/Xsession
index e12e0ee..ab94d28 100755
--- a/xinit/Xsession
+++ b/xinit/Xsession
@@ -30,6 +30,14 @@ SWITCHDESKPATH=/usr/share/switchdesk
# Xsession and xinitrc scripts which has been factored out to avoid duplication
. /etc/X11/xinit/xinitrc-common
+# RHEL6 GDM doesn't seem to support selectable sessions, and always requests a
+# gnome-session. So we unset this default here, to allow things like user
+# .xsession or .Xclients files to be checked, and /etc/sysconfig/desktop
+# settings (via /etc/X11/xinit/Xclients) honoured.
+if [ -n "$GDMSESSION" -a $# -eq 1 -a "$1" = gnome-session ]; then
+ shift
+fi
+
# This Xsession.d implementation, is intended to obsolte and replace the
# various mechanisms present in the 'case' statement which follows, and to
# eventually be able to easily remove all hard coded window manager specific
Apply as root:
cd /etc/X11
patch -p1 < /tmp/xsession.patch
Sun 09 Jan 2011
Tags: linux, sysadmin
Here's what I use to take a quick inventory of a machine before a rebuild,
both to act as a reference during the rebuild itself, and in case something
goes pear-shaped. The whole chunk after script up to exit is
cut-and-pastable.
# as root, where you want your inventory file
script $(hostname).inventory
export PS1='\h:\w\$ ' # reset prompt to avoid ctrl chars
fdisk -l /dev/sd? # list partition tables
cat /proc/mdstat # list raid devices
pvs # list lvm stuff
vgs
lvs
df -h # list mounts
ip addr # list network interfaces
ip route # list network routes
cat /etc/resolv.conf # show resolv.conf
exit
# Cleanup control characters in the inventory
perl -i -pe 's/\r//g; s/\033\]\d+;//g; s/\033\[\d+m//g; s/\007/\//g' \
$(hostname).inventory
# And then copy it somewhere else in case of problems ;-)
scp $(hostname).inventory somewhere:
Anything else useful I've missed?
Fri 08 Oct 2010
Tags: sysadmin, centos, pxe
Problem: you've got a remote server that's significantly hosed, either
through a screwup somewhere or a power outage that did nasty things to
your root filesystem or something. You have no available remote hands,
and/or no boot media anyway.
Preconditions: You have another server you can access on the same
network segment, and remote access to the broken server, either through
a DRAC or iLO type card, or through some kind of serial console server
(like a Cyclades/Avocent box).
Solution: in extremis, you can do a remote rebuild. Here's the simplest
recipe I've come up with. I'm rebuilding using centos5-x86_64 version
5.5; adjust as necessary.
Note: dnsmasq, mrepo and syslinux are not core CentOS packages,
so you need to enable the rpmforge
repository to follow this recipe. This just involves:
wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.1-1.el5.rf.x86_64.rpm
rpm -Uvh rpmforge-release-0.5.1-1.el5.rf.x86_64.rpm
1. On your working box (which you're now going to press into service as a
build server), install and configure dnsmasq
to provide dhcp and tftp services:
# Install dnsmasq
yum install dnsmasq
# Add the following lines to the bottom of your /etc/dnsmasq.conf file
# Note that we don't use the following ip address, but the directive
# itself is required for dnsmasq to turn dhcp functionality on
dhcp-range=ignore,192.168.1.99,192.168.1.99
# Here use the broken server's mac addr, hostname, and ip address
dhcp-host=00:d0:68:09:19:80,broken.example.com,192.168.1.5,net:centos5x
# Point the centos5x tag at the tftpboot environment you're going to setup
dhcp-boot=net:centos5x,/centos5x-x86_64/pxelinux.0
# And enable tftp
enable-tftp
tftp-root = /tftpboot
#log-dhcp
# Then start up dnsmasq
service dnsmasq start
2. Install and configure mrepo
to provide your CentOS build environment:
# Install mrepo and syslinux
yum install mrepo syslinux
# Setup a minimal /etc/mrepo.conf e.g.
cat > /etc/mrepo.conf
[main]
srcdir = /var/mrepo
wwwdir = /var/www/mrepo
confdir = /etc/mrepo.conf.d
arch = x86_64
mailto = root@example.com
smtp-server = localhost
pxelinux = /usr/lib/syslinux/pxelinux.0
tftpdir = /tftpboot
[centos5]
release = 5
arch = x86_64
metadata = repomd repoview
name = Centos-$release $arch
#iso = CentOS-$release.5-$arch-bin-DVD-?of2.iso
#iso = CentOS-$release.5-$arch-bin-?of8.iso
^D
# (uncomment one of the iso lines above, either the DVD or the CD one)
# Download the set of DVD or CD ISOs for the CentOS version you want
# There are fewer DVD ISOs, but you need to use bittorrent to download
mkdir -p /var/mrepo/iso
cd /var/mrepo/iso
elinks http://isoredirect.centos.org/centos/5.5/isos/x86_64/
# Once your ISOs are available in /var/mrepo/iso, and the 'iso' line
# in /etc/mrepo.conf updated appropriately, run mrepo itself
mrepo -gvv
3. Finally, finish setting up your tftp environment. mrepo should have copied
appropriate pxelinux.0, initrd.img, and vmlinuz files into your
/tftpboot/centos5-x86_64 directory, so all you need to supply is an
appropriate grub boot config:
cd /tftpboot/centos5-x86_64
ls
mkdir -p pxelinux.cfg
# Setup a default grub config (adjust the serial/console and repo params as needed)
cat > pxelinux.cfg/default
default linux
serial 0,9600n8
label linux
root (nd)
kernel vmlinuz
append initrd=initrd.img console=ttyS0,9600 repo=http://192.168.1.1/mrepo/centos5-x86_64
^D
Now get your server to do a PXE boot (via a boot option or the bios or whatever),
and hopefully your broken server will find your dhcp/tftp environment and boot up
in install mode, and away you go.
If you have problems with the boot, try checking your /var/log/messages file on the
boot server for hints.
Mon 22 Mar 2010
Tags: dell, omsa, centos, rhel, linux, sysadmin
Following on from my IPMI explorations, here's the next
chapter in my getting-down-and-dirty-with-dell-hardware-on-linux adventures.
This time I'm setting up Dell's
OpenManage Server Administrator
software, primarily in order to explore being able to configure bios settings
from within the OS. As before, I'm running CentOS 5, but OMSA supports any of
RHEL4, RHEL5, SLES9, and SLES10, and various versions of Fedora Core and
OpenSUSE.
Here's what I did to get up and running:
# Configure the Dell OMSA repository
wget -O bootstrap.sh http://linux.dell.com/repo/hardware/latest/bootstrap.cgi
# Review the script to make sure you trust it, and then run it
sh bootstrap.sh
# OR, for CentOS5/RHEL5 x86_64 you can just install the following:
rpm -Uvh http://linux.dell.com/repo/hardware/latest/platform_independent/rh50_64/prereq/\
dell-omsa-repository-2-5.noarch.rpm
# Install base version of OMSA, without gui (install srvadmin-all for more)
yum install srvadmin-base
# One of daemons requires /usr/bin/lockfile, so make sure you've got procmail installed
yum install procmail
# If you're running an x86_64 OS, there are a couple of additional 32-bit
# libraries you need that aren't dependencies in the RPMs
yum install compat-libstdc++-33-3.2.3-61.i386 pam.i386
# Start OMSA daemons
for i in instsvcdrv dataeng dsm_om_shrsvc; do service $i start; done
# Finally, you can update your path by doing logout/login, or just run:
. /etc/profile.d/srvadmin-path.sh
Now to check whether you're actually functional you can try a few of the
following (as root):
omconfig about
omreport about
omreport system -?
omreport chassis -?
omreport is the OMSA CLI reporting/query tool, and omconfig is the
equivalent update tool. The main documentation for the current version of
OMSA is here.
I found the CLI User's Guide
the most useful.
Here's a sampler of interesting things to try:
# Report system overview
omreport chassis
# Report system summary info (OS, CPUs, memory, PCIe slots, DRAC cards, NICs)
omreport system summary
# Report bios settings
omreport chassis biossetup
# Fan info
omreport chassis fans
# Temperature info
omreport chassis temps
# CPU info
omreport chassis processors
# Memory and memory slot info
omreport chassis memory
# Power supply info
omreport chassis pwrsupplies
# Detailed PCIe slot info
omreport chassis slots
# DRAC card info
omreport chassis remoteaccess
omconfig allows setting object attributes using a key=value syntax, which
can get reasonably complex. See the CLI User's Guide above for details, but
here are some examples of messing with various bios settings:
# See available attributes and settings
omconfig chassis biossetup -?
# Turn the AC Power Recovery setting to On
omconfig chassis biossetup attribute=acpwrrecovery setting=on
# Change the serial communications setting (on with serial redirection via)
omconfig chassis biossetup attribute=serialcom setting=com1
omconfig chassis biossetup attribute=serialcom setting=com2
# Change the external serial connector
omconfig chassis biossetup attribute=extserial setting=com1
omconfig chassis biossetup attribute=extserial setting=rad
# Change the Console Redirect After Boot (crab) setting
omconfig chassis biossetup attribute=crab setting=enabled
omconfig chassis biossetup attribute=crab setting=disabled
# Change NIC settings (turn on PXE on NIC1)
omconfig chassis biossetup attribute=nic1 setting=enabledwithpxe
Finally, there are some interesting formatting options available to both
omreport, for use in scripting e.g.
# Custom delimiter format (default semicolon)
omreport chassis -fmt cdv
# XML format
omreport chassis -fmt xml
# To change the default cdv delimiter
omconfig preferences cdvformat -?
omconfig preferences cdvformat delimiter=pipe
Thu 11 Mar 2010
Tags: linux, centos, rhel, ipmi, dell
Spent a few days deep in the bowels of a couple of datacentres last week,
and realised I didn't know enough about Dell's DRAC base management
controllers to use them properly. In particular, I didn't know how to
mess with the drac settings from within the OS. So spent some of today
researching that.
Turns out there are a couple of routes to do this. You can use the Dell
native tools (e.g. racadm) included in Dell's
OMSA product, or you can use
vendor-neutral IPMI,
which is well-supported by Dell DRACs. I went with the latter as it's
more cross-platform, and the tools come native with CentOS, instead of
having to setup Dell's OMSA repositories. The Dell-native tools may give
you more functionality, but for what I wanted to do IPMI seems to work
just fine.
So installation is just:
yum install OpenIPMI OpenIPMI-tools
chkconfig ipmi on
service ipmi start
and then from the local machine you can use ipmitool to access and
manipulate all kinds of useful stuff:
# IPMI commands
ipmitool help
man ipmitool
# To check firmware version
ipmitool mc info
# To reset the management controller
ipmitool mc reset [ warm | cold ]
# Show field-replaceable-unit details
ipmitool fru print
# Show sensor output
ipmitool sdr list
ipmitool sdr type list
ipmitool sdr type Temperature
ipmitool sdr type Fan
ipmitool sdr type 'Power Supply'
# Chassis commands
ipmitool chassis status
ipmitool chassis identify [<interval>] # turn on front panel identify light (default 15s)
ipmitool [chassis] power soft # initiate a soft-shutdown via acpi
ipmitool [chassis] power cycle # issue a hard power off, wait 1s, power on
ipmitool [chassis] power off # issue a hard power off
ipmitool [chassis] power on # issue a hard power on
ipmitool [chassis] power reset # issue a hard reset
# Modify boot device for next reboot
ipmitool chassis bootdev pxe
ipmitool chassis bootdev cdrom
ipmitool chassis bootdev bios
# Logging
ipmitool sel info
ipmitool sel list
ipmitool sel elist # extended list (see manpage)
ipmitool sel clear
For remote access, you need to setup user and network settings, either at boot time
on the DRAC card itself, or from the OS via ipmitool:
# Display/reset password for default root user (userid '2')
ipmitool user list 1
ipmitool user set password 2 <new_password>
# Display/configure lan settings
ipmitool lan print 1
ipmitool lan set 1 ipsrc [ static | dhcp ]
ipmitool lan set 1 ipaddr 192.168.1.101
ipmitool lan set 1 netmask 255.255.255.0
ipmitool lan set 1 defgw ipaddr 192.168.1.254
Once this is configured you should be able to connect using the 'lan' interface
to ipmitool, like this:
ipmitool -I lan -U root -H 192.168.1.101 chassis status
which will prompt you for your ipmi root password, or you can do the following:
echo <new_password> > ~/.racpasswd
chmod 600 ~/.racpasswd
and then use that password file instead of manually entering it each time:
ipmitool -I lan -U root -f ~/.racpasswd -H 192.168.1.101 chassis status
I'm using an 'ipmi' alias that looks like this:
alias ipmi='ipmitool -I lan -U root -f ~/.racpasswd -H'
# which then allows you to do the much shorter:
ipmi 192.168.1.101 chassis status
# OR
ipmi <hostname> chassis status
Finally, if you configure serial console redirection in the bios as follows:
Serial Communication -> Serial Communication: On with Console Redirection via COM2
Serial Communication -> External Serial Connector: COM2
Serial Communication -> Redirection After Boot: Disabled
then you can setup standard serial access in grub.conf and inittab on com2/ttyS1
and get serial console access via IPMI serial-over-lan using the 'lanplus' interface:
ipmitool -I lanplus -U root -f ~/.racpasswd -H 192.168.1.101 sol activate
which I typically use via a shell function:
# ipmi serial-over-lan function
isol() {
if [ -n "$1" ]; then
ipmitool -I lanplus -U root -f ~/.racpasswd -H $1 sol activate
else
echo "usage: sol <sol_ip>"
fi
}
# used like:
isol 192.168.1.101
isol <hostname>
Further reading: