[Pvfs2-developers] Simple stripe default values?

[Sam Lang]

Esteban,

All the I/O servers are striped across by default.  If you want to  
limit the number of servers striped across, you can do so by setting  
an extended attributed on the _directory_ where you create the file:

setfattr -n user.pvfs2.num_dfiles -v "4" /pvfs/my-dir/

Alternatively, you can set the default stripe width for all files in  
the filesystem with a config option in the file server config:

DefaultNumDFiles 4

This goes in the <FileSystem> context.

-sam


On Aug 5, 2008, at 6:18 PM, Esteban Molina-Estolano 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
>> <eestolan at lanl.gov> 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
>>> Pvfs2-developers at beowulf-underground.org
>>> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers
>>>
>>
>>
>>
>> --
>> Kyle Schochenmaier
>>
>
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