The per-file metadata setting for the number of IO nodes that the file
exists on is called num_dfiles.
This setting is controlled by the distribution and is located inside
the directory the file exists in.
The default behavior is to have num_dfiles be equal to the number of
IO nodes in the filesystem.
I'm not sure exactly where the code is to get the information from the
config file all the way to the distribution, but the distribution
layer receives the number of IO nodes and sets the metadata for the
`default` num_dfiles.
check out
pvfs2/src/io/description/dist-simple-stripe.c
The FAQ page has information about how to manually setup the
distribution parameters.
Hope this helps,
Kyle
On Tue, Aug 5, 2008 at 6:18 PM, Esteban Molina-Estolano
<[EMAIL PROTECTED]> wrote:
> Thanks for your help!
>
> I think I was unclear about the number of I/O nodes, though. I looked at
> the filesystem config file generated by pvfs2-genconfig and I can see the
> list of I/O nodes, but I'm not looking for the total number of I/O nodes.
> Rather, I'm looking for the per-file metadata setting that determines how
> many I/O nodes the file is actually striped across. Where can I find how
> this value is set by default?
>
> Thanks,
> ~ Esteban
>
>> stripe_size is in include/pvfs2-dist-single-stripe.h
>> the base IO node is determined in a round-robin fashion so 10 files
>> will ideally start on 10 different servers, if you had 10 servers.
>> number of io nodes comes down through the distribution, and initally
>> from the filesystem config file, I believe.
>>
>> Kyle
>>
>> On Mon, Aug 4, 2008 at 2:55 PM, Esteban Molina-Estolano
>> <[EMAIL PROTECTED]> wrote:
>>> I'm researching placement algorithms for different large-scale
>>> filesystems
>>> using trace-driven simulation, and I'm trying to write a simulator for
>>> the
>>> PVFS simple stripe placement algorithm.
>>>
>>> There's one detail I haven't been able to find in any documentation: how
>>> the values for the base I/O node number, number of I/O nodes, and stripe
>>> size are selected, by default, for each file.
>>>
>>> So far I've looked through the docs on the website, the dev mailing
>>> list,
>>> the 2000 paper ("PVFS: A Parallel Virtual File System for Linux
>>> Clusters"), the document "PVFS2 Distribution Design Notes", and the
>>> simple
>>> stripe placement code (dist-simple-stripe.c).
>>>
>>> Where else should I be looking for these default settings?
>>>
>>> Thanks,
>>> ~ Esteban Molina-Estolano
>>> _______________________________________________
>>> Pvfs2-developers mailing list
>>> [email protected]
>>> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers
>>>
>>
>>
>>
>> --
>> Kyle Schochenmaier
>>
>
>
--
Kyle Schochenmaier
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