[Lustre-discuss] lfs setstripe

[Kaizaad Bilimorya]

On Thu, 17 Apr 2008, Brock Palen wrote:
> I don't think you need to do this.
> If i understand right, you can set the stripe size of the mount, and 
> everything inside that directory inherits it, unless they them self's were 
> explicitly set.

Hi Brock, thanks for the reply.

I have set the stripe count on the lustre mount using "lfs setstripe" but 
the problem is that any sub directories that already existed under this 
mount will have the default filesystem stripe count and not the new one I 
set, so any new files created under these existent sub directories will 
inherit their parent directory stripe count and not the newly set one 
from the lustre mount.

eg:

/lustremount -> "lfs setstripe /lustremount 0 -1 2"
/lustremount/existing_dir -> has filesystem default stripe count (1 in 
this case)
/lustremount/new_dir -> gets stripe count of parent (2 in this case)
/lustremount/existing_dir/newfile -> has filesystem default stripe count 
of 1

So that is why I have to do either option 1 (change default) or 2 
(traverse and set explicitly for all existing dirs) that I specified, but I 
would like to know if there are any performance or other reasons not to do 
option 2.

thanks
-k

> Also files that already are created will keep the stripe settings they were 
> created with.  You would need to copy them, and move over the old one to 
> change to the new stripe settings.  Check the lustre manual they have 
> something about this.
>
> On Apr 17, 2008, at 10:34 AM, Kaizaad Bilimorya wrote:
>> Hello,
>> 
>> I would like to adjust the stripe count for our lustre filesystem. Would
>> it be better to:
>> 
>> 1) Kill all jobs, unmount the lustre filesystem from all clients, and then
>>     adjust the default stripe count for the lustre filesystem on the MDS
>>     using lctl.
>> 
>> or
>> 
>> 2) Use "find" and the "lfs setstripe" command to traverse and set the
>>     stripe count for all directories in a currently mounted lustre
>>     filesystem.
>> 
>> 
>> Besides the traversal cost of the filesystem, are there other
>> disadvantages, performance reasons, or other reasons not to use option 2?
>> 
>> thanks
>> -k
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>> 
>