[Pvfs2-developers] [PATCH] modify twod-stripe's default params and add some documentation

[Rob Ross]

I agree that it's best to have it work for everyone with default  
parameters.

-- Rob

On Jul 1, 2008, at 4:15 PM, "Kyle Schochenmaier" <kschoche at gmail.com>  
wrote:

> We should use simple stripe in that case, which is why i have it
> defaulted to it now, someone was playing with twod-dist today and
> noticed that it defaults to having 2 groups, which causes errors when
> you run it on only a single server.   I would much rather have the
> defaults allow the distribution to work on *any* setup, rather than
> just a n>1 servers setup.
>
> Its not particularly useful, but I belive it is the right thing to do,
> maybe I'm wrong?
> (the original default settings are worthless for my applications so I
> have to change them anyhow)
>
> Kyle
>
> On Tue, Jul 1, 2008 at 4:04 PM, Sam Lang <slang at mcs.anl.gov> wrote:
>>
>> Kyle,
>>
>> How is this patch useful for you guys?  With a single server (and  
>> only one
>> stripe), it doesn't matter what the factor and num_groups are, does  
>> it?  It
>> still behaves the same as simple-stripe in that case.  With  
>> multiple servers
>> setting the factor and num_groups to 1 does make the 2d  
>> distribution act
>> like simple-stripe, but why not just use simple stripe in that case?
>>
>> -sam
>>
>>
>> On Jul 1, 2008, at 3:19 PM, Kyle Schochenmaier wrote:
>>
>>> Patch is against cvs head, and modifies the default num_groups to  
>>> be 1
>>> and the group_strip_factor = 1  so twod-stripe's defaults still work
>>> when you use it on a single-server, it will now by default behave  
>>> the
>>> same as simple-stripe until the user modifies the num_groups and
>>> strip_factor xattrs.
>>>
>>> Also added a brief description of the definitions for the  
>>> dist_params
>>> in twod-stripe.
>>>
>>> Tested fully functional on my servers.
>>>
>>> Kyle
>>>
>>>
>>> Index: src/io/description/dist-twod-stripe.c
>>> ===================================================================
>>> RCS file: /anoncvs/pvfs2/src/io/description/dist-twod-stripe.c,v
>>> retrieving revision 1.5
>>> diff -r1.5 dist-twod-stripe.c
>>> 6a7,15
>>>>
>>>> /* twod-stripe will take all of the servers in the filesystem and
>>>> * partition them into num_groups groups.  Data will then be  
>>>> striped to
>>>> * each group before we move onto the next group.  The  
>>>> strip_factor will
>>>> * determine how many chunks of strip_size are written to each  
>>>> server
>>>> * in each group before we transition to the next group.
>>>> * The striping on the group level is done round-robin in the same
>>>> * fashion as simple-stripe
>>>> */
>>>>
>>>
>>>
>>> Index: include/pvfs2-dist-twod-stripe.h
>>> ===================================================================
>>> RCS file: /anoncvs/pvfs2/include/pvfs2-dist-twod-stripe.h,v
>>> retrieving revision 1.4
>>> diff -r1.4 pvfs2-dist-twod-stripe.h
>>> 17c17
>>> < #define PVFS_DIST_TWOD_STRIPE_DEFAULT_GROUPS 2
>>> ---
>>>>
>>>> #define PVFS_DIST_TWOD_STRIPE_DEFAULT_GROUPS 1
>>>
>>> 19c19
>>> < #define PVFS_DIST_TWOD_STRIPE_DEFAULT_FACTOR 256
>>> ---
>>>>
>>>> #define PVFS_DIST_TWOD_STRIPE_DEFAULT_FACTOR 1
>>>
>>>
>>> -
>>> Kyle Schochenmaier
>>> <twod-dist.patch>_______________________________________________
>>> 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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