Wednesday, February 25, 2009

Conky System Monitor for X

Conky is a free, light-weight system monitor for X, that displays any information on your desktop

Monday, February 23, 2009

EXT3-fs error (device hda3) in start_transaction: Journal has aborted

Taken from Racker Hacker *(

If your system abruptly loses power, or if a RAID card is beginning to fail, you might see an ominous message like this within your logs:

EXT3-fs error (device hda3) in start_transaction: Journal has aborted

Basically, the system is telling you that it’s detected a filesystem/journal mismatch, and it can’t utilize the journal any longer. When this situation pops up, the filesystem gets mounted read-only almost immediately. To fix the situation, you can remount the partition as ext2 (if it isn’t your active root partition), or you can commence the repair operations.

If you’re working with an active root partition, you will need to boot into some rescue media and perform these operations there. If this error occurs with an additional partition besides the root partition, simply unmount the broken filesystem and proceed with these operations.
Remove the journal from the filesystem (effectively turning it into ext2):

# tune2fs -O ^has_journal /dev/hda3

Now, you will need to fsck it to correct any possible problems (throw in a -y flag to say yes to all repairs, -C for a progress bar):

# e2fsck /dev/hda3

Once that's finished, make a new journal which effectively makes the partition an ext3 filesystem again

# tune2fs -j /dev/hda3

You should be able to mount the partition as an ext3 partition at this time:

# mount -t ext3 /dev/hda3 /mnt/fixed

Be sure to check your dmesg output for any additional errors after you’re finished!

Tuesday, February 17, 2009

Interesting Scientific OpenSource Applications

FFTW is a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine transforms or DCT/DST). We believe that FFTW, which is free software, should become the FFT library of choice for most applications.

Friday, February 6, 2009

Checking a program whether it is 32-bits or 64-bits

Can use the File Package
#file Program

Installed by default by CentOS