[Beowulf] Building new cluster - estimate
matt at technoronin.com
Mon Aug 4 13:54:19 PDT 2008
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 188.8.131.52 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 184.108.40.206 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.
It's not what I know that counts.
It's what I can remember in time to use.
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