[Beowulf] storage server hardware considerations
hahn at mcmaster.ca
Wed Jul 15 21:57:56 EDT 2009
>> Rather than looking at the solution, could you describe the problem you
>> need to solve?
> I've been building cheap, big, slow storage servers for our use. However,
> some of our users are starting to need higher performance IO. We still don't
> have a lot of money, but I'd like to provide something with a modest amount
> of storage (at least 500GB) that can at least handle full GigE, perhaps up to
> DDR Infiniband for future expansion, without breaking the bank.
if you can't saturate gigabit with very modest raids,
you're doing something wrong. a single ultra-cheap disk
these days (seagate 7200.12 500G, $60 or so) will hit
close to 135 MB/s on outer tracks and average > 105 over
the whole disk. I'm guessing that you're losing performance
due to either bad controllers (avoid HW raid on anything that's
not fairly recent) or a combination of raid6 and a write-heavy workload...
bandwidth is easy; latency is hard. the only time I'd consider flash
for storage is if the workload was astonishingly write-dominated. or
for a pretty large cluster (for instance, the metadata write load for
a a few thousand jobs can _flatten_ an indifferently configured Lustre
system, even though the bandwidth is fairly low.
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