Shrinking an ext4 filesystem from the CentOS 5.x CD/DVD in rescue mode

Unfortunately this cannot be done because the resize4fs program is missing from the rescue filesystem. You'll have to use a rescue distro, for example gparted-live, where the ext4 capabilities are already incorporated into the up to date resize2fs. CentOS/RHEL 5 ships with an old resize2fs and ext4 capabilities are in separate programs.

If it were a matter of expanding the filesystem this could be done on a live system.

If it were not the root filesystem you might be able to unmount the file system and do this on a live filesystem.

If it were not ext4 you could use resize2fs.

In any case a shrink involves downtime for that filesystem.

There is however a fsck.ext4 in the rescue filesystem so you can still do fscks in rescue mode.

Install tmm, matplotlib, scipy and numpy on CentOS/RHEL 5

I hope this post saves you some searching if you have to go through the same steps as I did.

A user at this site wanted to run tmm for simulations on CentOS 5 servers.

CentOS/RHEL 5 unfortunately comes with python 2.4, too old for the required modules. Fortunately there is an easy way to install python 2.6 side by side and that is to get the python26 package from EPEL. If you do:

yum search python26

you will get a list of python26 packages. Aside from the base python26 package, I also needed python26-numpy. This will pull in any dependencies. When you have installed python26 you must remember to invoke python scripts with python26 or to edit the #! first line.

The scipy module was installed from source, that was the easiest way. Then I installed the tmm module. BTW in all the python extension installs I used python26 setup.py install rather than any package manager.

After that the test.py program in the tmm distribution ran. But my user pointed out that examples.py didn't run. This requires matplotlib. Ok, installed that from source. Now the function sample1() in examples.py ran, but generated no output. More searching showed that you have to specify the backend in ~/.matplotlib/matplotlibrc like this:

backend: TkAgg
interactive: true

(I'm leaving out some useless experiments involving the Postscript backend.) This generated an error about Tkinter not loading. I went back and looked at the setup step for matplotlib and noticed that when I ran:

python26 setup.py

it said I didn't have the Tkinter header files installed so it wasn't building the interface for the Tkinter backend. So I did yum install tk-devel, built and installed matplotlib again, and finally I got the example program to display a plot.

Whew!