[Pvfs2-users] PVFS2 directory attributes

[Phil Carns]

Xuechen and I continued this discussion off list and found that varstrip 
is not the right tool for the job.  It does not control which servers 
are used and also does not let you start at an arbitrary strip as I 
suggested in the B example.

Right now we don't really have hooks in PVFS to control the layout this 
specifically at a directory level.

-Phil

Phil Carns wrote:
> Hi Xuechen,
> 
> I believe that this is possible with the varstrip distribution in PVFS. 
>  Here is some further information:
> 
> http://www.pvfs.org/fisheye/browse/PVFS/doc/pvfs2-tuning.tex?r=1.1.22.1#l328 
> 
> 
> For example, I think on directory A you would set something like:
> 
>   setfattr -n user.pvfs2.dist_name -v varstrip_dist A
>   setfattr -n user.pvfs2.dist_params -v "strips:0:64K;1:64K" A
> 
> And this for B:
> 
>   setfattr -n user.pvfs2.dist_name -v varstrip_dist B
>   setfattr -n user.pvfs2.dist_params -v "strips:2:64K;3:64K" B
> 
> That should automatically set the number of datafiles to 2 based on the 
> distribution parameters, but it is possible that some previous releases 
> didn't do that.  If you have trouble use these commands to make it 
> explicit:
> 
>   setfattr -n user.pvfs2.num_dfiles -v "2" A
>   setfattr -n user.pvfs2.num_dfiles -v "2" B
> 
> A few other misc. pointers:
> 
> - this only affects new files in any given directory and does not change 
> existing files
> 
> - make sure to test the results by using "pvfs2-viewdist -f <filename>" 
> to see how new files are distributed
> 
> -Phil
> 
> Xuechen Zhang wrote:
>> There is a question about setting PVFS2 directory attributes. I have 
>> four I/O servers (0-3). I want to locate file A in directory A on 
>> server 0&1 and file B in directory B on server 2&3 by settting stripe 
>> distribution for the two directory. Can I implement this kind of 
>> distribution in PVFS2? If not, any suggestion for that? Thanks.
>>
>> Xuechen
>>
>>
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