Category: Sysadmin

System administration is a special are of IT. It also has a special place in my heart. It is an interesting mixture of all the other disciplines, both common across the whole industry, and at the same time unique for each person, company, and geographical location. When I have something to say or share about system administration, I use this category.

Monitoring tree of Linux processes

Once in a while there is a need to see the tree of processes on a Linux system.  When such a need arises, I usually run “ps auxw –forest“, which results in something like this (partial output, top only):

/bin/ps auxw --forest

Today, via this blog post, I’ve learned that there is another way – “pstree“.  This command accepts a number of parameters, but in its simplest form, results in something like this (partial output, top only):

/usr/bin/pstree

On my Fedora box, /usr/bin/pstree is a part of the psmisc RPM, which is the one that brings /usr/bin/killall to the system.

On scalability of MySQL

Anyone who says that MySQL is not scalable has no idea.  Facebook is one of the examples for a large deployment of MySQL:

How big is Facebook’s Internet infrastructure? Facebook VP of Technology Jeff Rothschild provided some details in a panel at the recent MySQL user conference. Rothschild says Facebook is now running 10,000 servers, including 1,800 MySQL servers that are overseen by just two database administrators.

Facebook recently surpassed 500,000,000 users – half a billion!

Integrating RT3 with Subversion

As I have mentioned a few times before, I am a big fan of using BestPractical RT3 for all sorts of things, including, but not limited to, bug tracking during project development.  I see a great benefit in having a single system for both technical support and development departments.  Bugs can be reported by customers, investigated by technical support department, passed on to developers, fixed and tested, and then passed back to technical support department to verify with the customer and resolve.

Needless to say, integrating RT3 with Subversion can be of great benefit.  In this case, not only you will have full history of bug reports, but you’ll also see which code changes were made for each bug report.  Learning from previous bug fixes and having a quick way to see why something was changed is priceless.

Read more to see how RT3 can be integrated with Subversion.  You can also easily adopt the same approach to other version control systems.

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Zip vs. Bzip2

While investigating an unrelated issue on our backup server, I came across an interesting discussion about gzip vs. bzip2. I was surprised to read on how much slower bzip2 is.  I even tested it on our server.  And as expected, I saw the huge difference.

$ du -sh home
819M  home

$ time tar czf test.tar.gz home
real	3m29.741s
user	1m4.026s
sys	0m5.629s

$ time tar cjf test.tar.bz2 home
real	11m38.751s
user	6m19.259s
sys	0m7.237s

$ ll test.tar*
-rw-r--r-- 1 leonid users 365987716 2010-06-29 13:08 test.tar.bz2
-rw-r--r-- 1 leonid users 390655750 2010-06-29 12:56 test.tar.gz

For such a small difference in size, the compression time difference is huge! Of course, I should play with more parameters, repeat the tests several times, and test the decompression time too. But the above test is still a good indication. Way too many scripts out there use the default parameters and substitute gzip with gzip2 without any testing. That’s obviously asking for trouble.

MantisBT vs. RT3

I’ve been praising Best Pratical’s RT3 (aka Request Tracker) for a long time.  So at my new job, given a new start, I thought that I maybe need to explore other options and widen my horizons.  After all, the needs were much less and much simpler.  We just needed a bug tracking application for three people or so and for a single project.  There was a possibility of more people joining the team later and more projects starting up, so I didn’t want to limit ourselves too much.  But immediate needs were quite simple.

After a good look around, I decided to give Mantis Bug Tracker another try.  I remember using it for a bit back when the project just started.  I even remember patching it to fit my needs back then.

During those few years that I haven’t looked at MantisBT it grew and developed quite a bit.  It is a stable, feature-rich, yet simple to manage application.  We’ve used it for the whole two month before our needs changed again and we started looking back at RT3.  Never-the-less I am glad we used it and got experience with another tool.  I got a few ideas out of it, which I will be implementing in our new RT3 installation.  Below are the few things that I loved and hated about the MantisBT.  Maybe you’ll find them useful.

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