Slow fsck on adaptec SAS/SATA raid

[tytso at mit.edu]

On Wed, Jan 20, 2010 at 12:30:35PM -0500, Doug Warner wrote:
> I'm trying to do an fsck on an ext3 partition but I'm seeing abysmally slow
> disk throughput; monitoring with "dstat" (like vmstat) shows ~1200-1500KB/s
> throughput to the disks.  Even with 24hrs of fsck-ing I only get ~3% (still in
> pass1).
> 
> The filesystem is ext3 running "e2fsck -C0 /dev/sda3" and about 3.7TB on an
> x86_64-based system with 4GB RAM.  e2fsprogs is 1.41.9.
> 
> During initial periods of the fsck I see throughput in the 30-70MB/s range
> (ie, <0.4% complete).  Shortly after that throughput tanks and stays there.
> Just a rough extrapolation of the size of my filesystem (3.4TB used; ~95%)
> makes it look like this will take ~28 days to complete.  I'm using approx 12M
> inodes out of my 243M available.

Are you using some kind of backup scheme that creates huge number of
hard links to files?  E2fsck could be thrashing due to lack of memory
space.   

					- Ted