[OpenAFS] improving cache partition performance

Dale Pontius pontius@btv.ibm.com
Mon, 29 Aug 2011 07:54:40 -0400

On 08/28/2011 05:00 PM, Jason Edgecombe wrote:
> hi everyone,
> I'm looking at some performance problems on our web servers, and I 
> think that hard drive performance is a bottleneck. All filesystems are 
> on a RAID0 disk array with two 7200RPM disks (no battery-backed 
> cache). The cache is on a dedicated ext3 partition. At some points, my 
> await times on the disk are up to 1000ms. How can I improve this? 
> Would setting commit time larger than 5 seconds be OK? Would setting 
> the ext3 journal type to "data=writeback" be OK?
> platform: RHEL5.5 x86_64
For starters, I'd use ext2 instead of ext3, or perhaps use ext4 with 
journaling turned off.  I seem to remember once hearing that having 
journaling on for the afs cache partition was even bad, as opposed to 
merely slightly slower.  It's just a cache, it's never all that big, and 
if fsck were to have problems, it's easier to just plain wipe and start 

Dale Pontius

Dale Pontius
Senior Engineer
IBM Corporation
Phone: (802) 769-6850
Tie-Line: 446-6850
email: pontius@us.ibm.com

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