Matt Lawrence wrote:
On Mon, 4 Aug 2008, Joe Landman wrote:
This mirrors our experience, though RHEL stability under intense
loads is questionable IMO (talking about the kernel BTW). We find
that the missing drivers, the omitted drivers, the backported drivers
along with some odd and often useless "features" (4k stacks anyone?)
render the RHEL default kernels (and by definition the Centos
kernels) less useful for HPC and storage tasks than what we build.
Our current standard is a 2.6.23.14 kernel which is rock solid under
load. Working on a 2.6.26 based version now (even though I am on
vacation/holiday, I just updated it to 2.6.26.1 to address an
observed crashing issue with the RDMA server)
Since I plan to continue running CentOS, it sounds like building a
much later kernel rpm is the way I want to approach the problem. Will
going to a much later kernel break any of the utilities? Other
problems I can expect to see?
What do you recommend for the kernel config?
Combine this with the small upper limit of ext3 partition sizes, the
file size limits in ext3, the serialization in the journaling code
(ext4 is extents based to help deal with this), ext3 just doesn't
make much sense in a storage/HPC system (apart from possibly
boot/root file system where performance is less critical). Yeah I
have seen studies from folks whom had done 1E6 removes, file creates,
and other things who claim xfs is slower than ext3. Yeah, those are
bad benchmarks in that they really don't touch on real end user use
cases for the most part (apart from possible large scale mail servers
and other things like that).
I have never had any problems with ext3. I had dinner with a friend
who is an expert Linux sysadmin who was warning me to stay away from
xfs. He cited lots of fragmentation problems that routinely locked up
his systems. I am willing to be convinced otherwise, but he is a very
sharp fellow.
Check the kernel mailing list for XFS problems with RAID5 if you use
mdadm...jsut a gentle suggestion ;)
-- Matt
It's not what I know that counts.
It's what I can remember in time to use.
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