[Pvfs2-users] Re: Performance of varstrip_dist configures as a stripe verses simple_stripe

[Phil Carns]

Tony Kew wrote:
> Dear Phil,
> 
> Phil Carns wrote:
>> Tony Kew wrote:
>> [...]
>>> The test dir was set up with 16K strips on each node for a 1024K stripe.
>>> iozone set up to write in 1024K blocks.  The job took about an hour and
>>> five minutes to run...
>>>
>>> Initial write 668,321.05 KB/sec
>>>       Rewrite 677,999.64 KB/sec
>>>          Read 300,937.30 KB/sec
>>>       Re-read 313,756.56 KB/sec
>>
>> You realize that you can create this same setup with the default 
>> simple stripe distribution too if you use a 16K strip size, right?
>>
>> [...]
> 
> Yes, I just wanted a test I could then compare with the results of similar
> distributions using the simple_stripe and twod_stripe distributions.
> In my tests so far varstrip_dist set up to be the same as a simple_stripe
> is slower, markedly slower when the filesystem is on the same nodes
> as iozone is running on (i.e. an "on the fly" filesystem built across
> the nodes in a PBS job)  - I don't know if this is what you might reasonably
> expect
> 
> from 
> http://www.ccr.buffalo.edu/display/WEB/PVFS+version+2+scratch+filesystem+on+U2+-+Test+Results

Hi Tony,

Thanks for sharing that data- that's really interesting.  It looks like 
something in the varstrip distribution must be adding quite a bit of 
computational complexity.

-Phil