/var/lib/ureadahead/debugfs And Disk Space “Recovery” In Ubuntu 10.04

And happy new year.

I had thought this was something involving Gaussian09 memory usage until I restarted a machine and found the same problem occurring in Ubuntu. Below is a quick fix (and reminder for the future).

Checking disk space with df -all :

user@machine:~$ df -all
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1            147550696   5863896 134191632   5% /
proc                         0         0         0   -  /proc
none                         0         0         0   -  /sys
none                         0         0         0   -  /sys/fs/fuse/connections
none                         0         0         0   -  /sys/kernel/debug
none                         0         0         0   -  /sys/kernel/security
none                   3053752       260   3053492   1% /dev
none                         0         0         0   -  /dev/pts
none                   3058264         0   3058264   0% /dev/shm
none                   3058264        84   3058180   1% /var/run
none                   3058264         0   3058264   0% /var/lock
none                   3058264         0   3058264   0% /lib/init/rw
none                         0         0         0   -  /var/lib/ureadahead/debugfs
nfsd                         0         0         0   -  /proc/fs/nfsd
binfmt_misc                  0         0         0   -  /proc/sys/fs/binfmt_misc

… we find /var/lib/ureadahead/debugfs both existing but taking up no space to speak of. Several seconds later (after a reboot), we find the following…

user@machine:~$ df -all
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1            147550696   5864268 134191260   5% /
proc                         0         0         0   -  /proc
none                         0         0         0   -  /sys
none                         0         0         0   -  /sys/fs/fuse/connections
none                         0         0         0   -  /sys/kernel/debug
none                         0         0         0   -  /sys/kernel/security
none                   3053752       260   3053492   1% /dev
none                         0         0         0   -  /dev/pts
none                   3058264         0   3058264   0% /dev/shm
none                   3058264        84   3058180   1% /var/run
none                   3058264         0   3058264   0% /var/lock
none                   3058264         0   3058264   0% /lib/init/rw
none                 147550696   5864268 134191260   5% /var/lib/ureadahead/debugfs
nfsd                         0         0         0   -  /proc/fs/nfsd
binfmt_misc                  0         0         0   -  /proc/sys/fs/binfmt_misc

Properly updated machines (as per below) both do not contain this /var/lib/ureadahead/debugfs directory and do not subsequently “blow up” and eat disk space (to date. This may not be the real problem, but disk space usage will increase to +60% and, to my mind, the machine will noticeably slow down).

Fix Steps:

sudo aptitude update
sudo aptitude upgrade

Update your 10.04. Some web pages report that the problem with /var/lib/ureadahead/debugfs is attributable to a bug in mountall (now fixed. See bugs.launchpad.net/ubuntu/+source/mountall/+bug/736512).

sudo mv /etc/init/ureadahead.conf /etc/init/ureadahead.conf.disable

If you do NOT perform this move, the machine restart will produce the same /var/lib/ureadahead/debugfs error above. Kudos to ubuntuguide.net/howto-fix-ureadahead-problem-after-upgrading-to-ubuntu-10-04 for pointing this out.

sudo shutdown -r now

System restart, problem (for me, at least) solved.

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