[Beowulf] Network Filesystems performance

[Chris Samuel]

On Mon, 19 Nov 2007, Ashley Pittman wrote:

> On Sat, 2007-11-10 at 18:33 +1100, Chris Samuel wrote:
>
> This is an interesting proposition, you seem to imply it's easier
> to change distribution that it is to customise the one you are
> already using, I'm wondering what your reasoning for this is.

Because we build a new storage server on a spare box with the new 
distro and then move the storage hardware onto it (save the first 
transition from RHEL to Fedora, where we used a couple of Opteron 
nodes from a test system and an Apple XServe RAID to replace the IBM 
x345 and the FAStT600).

> Granted in theory it *should* be easy to change distro and it has
> getting easier as they have become more and more homogeneous over
> time but equally replacing the RedHat Kernel with one that supports
> XFS isn't the end of the world either.

No, but given the only reason we were using RHEL in the first place 
was because of the FC multipath support with 2 controllers in the 
FAStT600 which IBM would only support under RHEL or SLES (and we had 
no SLES systems at the time) it was easier to move to a better 
distro.

> Are you choosing a distro which you can run un-modified and hence
> buy support for or do you genuinely believe it's easier to learn
> and support a new distro than it is to install a new kernel on the
> current one?

We prefer distros that work out of the box in the way we expect. RHEL 
does not qualify as that for us.

Debian does.

Paid support does not necessarily translate to a working system 
(witness a SLES9 upgrade to yaboot which had a minor bug - it didn't 
work on OpenPOWER 720 systems - fortunately we tried it on a test 
node which we reverted to the previous version - took a while for 
them to get around and fixing the problem we reported).

> Personally I've always been of the opinion that you should pick a
> distro based on what you have experience of in-house and then modify
> that distro to meet your needs rather than the other way around.

Yup, that's our preference too - problem is that commercial software 
(and hardware) vendors tend to have different ideas (grr).

Chris
-- 
Christopher Samuel - (03) 9925 4751 - Systems Manager
 The Victorian Partnership for Advanced Computing
 P.O. Box 201, Carlton South, VIC 3053, Australia
VPAC is a not-for-profit Registered Research Agency
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