Do you have a Windows DNS? and you need to add 300 A record on it… So do I!
In order do quickly do so, I wrote a small script: dnsupdate
you just need a txt file next to it called dnsupdate.txt populated by NAME,IP_ADDRESS (only 1 per line), and the script will go through the list and add an A entry for each of them.
Hope this will be useful for someone else :D
If you still use VMware GSX and/or VMware server 1, and some of your guest are Linux, you may have already encountered this issue. This might seems not useful as those VMware products are quite old now, but when it’s on production, you don’t really get rid of something easily :D
The clock of the system is always de-sync even with a ntp server configured on it. This is a big issue when you run automated script with cron, and you’re system backup is done at 10am instead of 5am… That’s because your CPU clock is running too fast or too slowly. This is a known issue on those product as they don’t support host power management features on Linux properly.
To sort this out, you just to do the following:
you first need to know your CPU speed
~cat /proc/cpuinfo | grep MHz cpu MHz : 3601.737
edit the file /etc/vmware/config and add
host.cpukHz = 3601737 host.noTSC = TRUE ptsc.noTSC = TRUE
host.cpukHz change depending the output of the fisrt command. It’s basically the CPU speed in Hz.
if not already done, you need to install the VMware tools on the guest and configure the time synchronisation. You can do it either by editing a file or in the options of the VM tools in a graphical interface.
The file to edit is the .vmx file and the line to add is tools.syncTime = “TRUE”
Once it’s all done, you’ll have to reboot the guest and restart VMware on the host.
If the problem is not fixed, this may be addressed by disabling power management altogether. This can be done by adding “apm=off acpi=off noapic” to the boot entry of the host’s /etc/grub.conf file.
I’ve got 2 TS-409 NAS appliance from QNAP. They are configured in raid5 and data are synchronised between them. As there is no possibilities to monitor the disk usage (no SNMP or any other things like that), I decided to create a little script which send an email when the disk usage reach 90%
This is not a big deal as it only contain few lines and is really straightforward, but I actually spent 2 hours to figure out how I could send this bloody email… Again, nothing difficult, just that I started in the wrong direction. i wanted to send it through a telnet connection on port 25 of the mail server… The only problem is that it was fine on any linux with a proper telnet binary, but the telnet implementation on busybox is different and doesn’t work when I try to telnet the smtp port of our exchange… So I just used ssmtp, already included and it works like a charm.
The script could obviously report a lot more but that’s what I’ve been asked :D
#!/bin/sh
FROM="FROM: Nas1@xxx.yyy"
TO="someone@xxx.yyy"
RCPT="TO: $TO"
SUB="Subject: Test Alert"
BODY="The NAS is filled at XXX%"
dfresult=`df -h /dev/md0 | grep /dev`
position=`expr index "$dfresult" %`
let position=$position-3
if [ ! ${dfresult:$position:1} == "" ];then
value=${dfresult:$position:2}
if [ $value -ge 90 ];then
BODY=${BODY/XXX/$value}
(echo "$RCPT";echo "$FROM";echo "$SUB";echo "";echo "$BODY") | ssmtp $TO
else
echo "not critical"
fi
else
echo "less than 10%"
fi
exit 0
It wouldn’t be difficult to add few more things like add how many GB left, and things like that but I’ll let you do it :D
Here we are! The new kernel has been released today after 8 release candidate and bring some interesting new features along driver update and bugfix. I won’t go into details but here are the main thinks:
As you can see there is quite a few new thinks about file systems. I might post something about all that as it’s been a quite busy area lately with EXT4, Btrfs, …
The Kernel 2.6.30 represents 11912 patches and one million and half lines of code modified, which makes it a quite big development cycle.
More details about the new drivers
This is just a quick look at what’s new on the Kernel, you can get much more informations there
I recently found a tool that help me a lot on my duties at work! It’s called PuTTy Connection Manager. No it’s not just the putty that everyone knows. It’s an application that actually come on top of putty to enhance it. As you can see below, the main feature is tabs. But don’t tell me, if you are an unfortunate user of putty like me (not that putty is not good but I’d prefer to use a Linux OS at work. Therefore, I wouldn’t have to use putty…), that you never thought that putty would be much better with tabs!!!
PuTTy Connection manager
PuTTy Connection Manager require the .NET framwork V2 and Encryption library 0.6.0.0 if you want to encrypt your database.
Unfortunately, the project (French :D) seems to be dead and it’s not open sources… But it got to a point where I don’t really need much more features and there is no important bug. If you know any PuTTy-like tools better than this one, and preferably still alive, let me know, it might be interesting :D
You can download the latest version here
And the website is here
Nothing new here but I’ll use this post as a quick reminder to enable kernel dump on red hat enterprise 4. Quite useful when you don’t know why your box keep crashing this week when it was perfectly fine for the last 2 years :D
Red Hat historically use netdump in order to save a kernel dump file but since RHEL 4, they introduced diskdump. Which is good as I don’t want to bother set-up a netdump server (even if there is few interesting thinks in favour of netdump, like “what if your system doesn’t recover…”). You can easily understand the main difference between them… The first one create the file over the network using a server (like if you have a syslog server) while the other one use a local disk.
Here the few steps to follow:
Everything should be already installed, but in case it’s not on your system:
# up2date crash diskdumputils
crash is an utility used to analyse the dump file.
Check the loaded kernel modules, if not already loaded, then do it.
# lsmod | grep diskdump # modprob diskdump
Configure what partition you want to use. 2 choices: 1st you have a partition only for this purpose, 2nd you can use a swap partition. if you don’t use a swap partition, you’ll have to format it. The size of the partition you choose must be at least the size of your ram.
# cat /proc/swaps # vi /etc/sysconfig/diskdump
You can specify more than one partition if you separate them by ‘:’
DEVICE=/dev/sda4:/dev/sda5
If you didn’t choose a swap partition, then you have to format your device in order use it as a dump device.
# service diskdump initialformat
Tell your system to start diskdump automatically at the next reboot and start it.
# chkconfig diskdump on # service diskdump start
If you get a warning, it may just means that your partition is not good (wrong partition specified in /etc/sysconfig/diskdump, or forgot to format, …)
check that the module works fine. the output must be something like the following:
# cat /proc/diskdump # sample_rate: 8 # block_order: 2 # fallback_on_err: 1 # allow_risky_dumps: 1 # dump_level: 0 # compress: 0 # total_blocks: 2097059 # sda4 4401810 4192965 sda5 8594838 4192902
When a crash occures, the data from the disk dump partition are not directly readable. You need to gather them in a file on a readable partition. This is done with the following command:
# savecore -vD /dev/sda4
You can add this command to /etc/rc.local if you want to run it automatically after a crash.
This is it! Next time your kernel crashes, you’ll get a file called vmcore stored in /var/crash/127.0.0.1-\
You can test if it works fine by doing one of the following things. It will result on you server crashing therfore creating a dumpfile.
# Alt-SysRq-C or # echo c > /proc/sysrq-trigger or # echo 1 > /proc/sys/kernel/sysrq
you can also quickly compile the following code [cc -c -I/usr/src/linux/include panic.c]
and load this nice module :D [insmod panic.o]
#### panic.c #####
#define __KERNEL__
# MODULE
# include init_module(void)
int init_module (void)
{
panic(" panic has been called");
return 0;
}
now in order to analyse your dump, crash require the kernel debuginfo package corresponding to the kernel you are running. You can find it there. Then you need to install it.
wget http://updates.redhat.com/enterprise/4AS/en/os/Debuginfo/i386/RPMS/
kernel-debuginfo-2.6.9-89.EL.i686.rpm && \
su -c "rpm -Uvh kernel-debuginfo-2.6.9-89.EL.i686.rpm"
After your kernel panic and a reboot, you can now run crash with the following arguments (vmlinux_path vmcore_path).
# crash /usr/lib/debug/lib/modules/2.6.9-89.EL/vmlinux \
/var/crash/127.0.0.1-2009-06-07-14\:44/vmcore
OUTPUT
KERNEL: /usr/lib/debug/lib/modules/2.6.9-89.EL/vmlinux
DUMPFILE: /var/crash/127.0.0.1-2009-06-07-14:44/vmcore
CPUS: 1
DATE: Tue Jun 8 15:02:44 2009
UPTIME: 00:51:24
LOAD AVERAGE: 0.05, 0.05, 0.00
TASKS: 81
NODENAME: rhxxx.test.xxx.org.uk
RELEASE: 2.6.9-89.EL
VERSION: #1 Fri Feb 24 16:44:51 EST 2006
MACHINE: i686 (3600 Mhz)
MEMORY: 1.5 GB
PID: 3514
COMMAND: "crash"
TASK: f562ecd0 [THREAD_INFO: f4b7d000]
CPU: 0
STATE: TASK_RUNNING (ACTIVE)
I leave you find out all the things you can do with crash (try a “man crash” or help
you can find much more details here
Enjoy :D
I needed to create a couple of diagram of the VM infrastructure we’ve got, but as usual for some specific things you want to design, I had first to spend a couple of hours googling to find some nice stencils for visio. I found some very nice one, and some template on other blogs or website, but I didn’t manage to find what I wanted for few of them, so I decided to create those who where missing. I ended up with 3 different cathegories. Hardware, virtualisation and other. Most of them are the real VMware drawing.
I also attached 3 template, as I found them nice and interesting. I modified them a little bit by using different stencils. I’m sure they will be useful for a lot of people.
For those who don’t have Visio (MS proprietary sory…) I’ll attach the PNG to use with any other alternative like Kivio, DIA or OpenOffice Draw. I first wanted to create a specific set of stencils for those 3 aplications (Kivio and DIA stencils are compatible), but it’s an horrible thing to do, I don’t have time to spend hours and hours doing stencils. Then I wanted to use the SVG format. perfect for this kind of things. Unfortunately, when you try to import a SVG in DIA, it doesn’t work… even if this is a “supported” format! There is a bug reported since 2006 still not corrected… So the easiest thing is to use PNG images. I attached them and at least it works even for visio! (the visio stencils are attached as well).
It’s pretty hard to find a good open source diagram software. When Draw is more like a Drawing software, a mix between Publisher and Visio, Kivio has got a lack of funcionalities, and DIA is buggy, not supported corectly by the gnome team, and hasn’t got much more functionalities than Kivio… This is shame, DIA is quite good and would have had the potencial to compete with visio. Anyway, my stencils are yet to be complete, and I will add some more later on.
You can download them with the links below:
VI3 Template
Virtualization Stencils
PNG files
The original visio teplate were found in the blog p2vd.com
Some of the stencils were found in veeam.com, and one or two in vmguru.com
Welcome to my brand new blog. I’ll try to talk about IT in general, but probably more specially about Linux, and VMware.
I’ve been using Linux as main OS for 3 years, maybe a bit more. Ubuntu most of the time for the desktop. Debian or Red Hat for servers. I’m an open source fellow, and even when I have to use windows, I try to stick to my ideas, always open source first :D
VMware as a second subjet might be a bit surprising after what you’ve just read, as it’s not an open source product and there is Xen to compete against it. Yes, but I think VMware is a much more complete product. It not for no reason that they are leader on the virtualization market!
Anyway, as I have to work on an heterogeneous environment, I’ll probably also post about Windows and some other things. So why “Linux os for me” as a name for this blog then? If you don’t just speak about Linux… Just because I like the pun :D Linux is an OS, but you could read it “Linux is for me” as well. And this is my favourite subject anyway…
Enjoy!!!