On Jul 17, 2007, at 11:52 AM, Florin Isaila wrote:
Hi Sam, we start the pvfs2 servers on different machines than the
compute nodes (picking the nodes from the list provided by the batch
system). Was that your question?
I was wondering if you used the storage hardware (the DDN 9500 with
the 16 Dell 1850s). Sounds like the answer is no, the servers were
running on 16 separate compute nodes with local SATA disks.
To answer your question, TroveMetaSync won't serialize IO
operations. In fact, IO operations in PVFS don't require updates at
the metadata servers at all.
-sam
And I should have said, all the measurements are done with collective
I/O of ROMIO.
On 7/17/07, Sam Lang <[EMAIL PROTECTED]> wrote:
Ah, I read your email wrong. Hmm...so writes really tank. Are you
using the storage nodes as servers, or other compute nodes?
-sam
On Jul 17, 2007, at 11:15 AM, Sam Lang wrote:
>
> Hi Florin,
>
> Just one clarification question...are those are bandwidth numbers
> not seconds as the plot label suggests?
>
> -sam
>
> On Jul 17, 2007, at 11:03 AM, Florin Isaila wrote:
>
>> Hi everybody,
>>
>> I have a question about the PVFS2 write performance.
>>
>> We did some measurements with BTIO over PVFS2 on lonestar at TACC
>> (http://www.tacc.utexas.edu/services/userguides/lonestar/)
>>
>> and we get pretty bad write results with classes B and C:
>>
>> http://www.arcos.inf.uc3m.es/~florin/btio.htm
>>
>> We used 16 I/O servers, the default configuration parameters
and upto
>> 100 processes. We realized that all I/O servers were used also as
>> metadata servers, but BTIO uses just one file.
>>
>> The times are in seconds, contain only I/O time (no compute
time) and
>> are aggregated per each BTIO run (BTIO performs several writes).
>>
>> TroveSyncMeta was set to yes (by default). Could this cause the I/
>> O to
>> be serialized? It looks as if there were a serialization.
>>
>> Or could the fact that all nodes were also launched as metadata
>> managers affect the performance?
>>
>> Any clue why this happens?
>>
>> Many thanks
>> Florin
>> _______________________________________________
>> Pvfs2-users mailing list
>> [email protected]
>> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
>>
>
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