Lustre discuss - Jan 2012 - How to write more databytes on a file if ost is full

Hello,

I use lustre 1.8.5 on Debian.

On lustre 1.8.5, if I have

- One OST with 1 To, 100 Mo free

I add a new OST with 1 To.

On the first ost, I want to add new databytes on a file (fseek at the end),
and I want to add 500 Mo, it''s fail because lustre can''t write
400 Mo on the
new OST.

So my questions are:
- Is there a solution on Lustre (2.0?)
- Others clusters have this problem?


Thanks

Yes, this is the expected behavior.  Lustre is (still) unable to change the
static stripe information after a file is created, so once a file is allocated
on an OST, if that OST becomes full, Lustre will not be able to grow the file
regardless of the space available on other OSTs.

The workaround for this issue is to "cp" the file to a temporary name
on the same file system, where it is likely to be allocated on the new OST with
free space, and then rename the new file over the old one.  Now repeat until you
have achieved the desired balance of free space.

lfs_migrate is a tool that automates this process somewhat.  See
http://wiki.lustre.org/manual/LustreManual20_HTML/UserUtilities_HTML.html#50438206_42260

Kevin


On Jan 26, 2012, at 7:09 AM, Eudes wrote:
> Hello,
> 
> I use lustre 1.8.5 on Debian.
> 
> On lustre 1.8.5, if I have
> 
> - One OST with 1 To, 100 Mo free
> 
> I add a new OST with 1 To.
> 
> On the first ost, I want to add new databytes on a file (fseek at the end),
> and I want to add 500 Mo, it''s fail because lustre can''t
write 400 Mo on the
> new OST.
> 
> So my questions are:
> - Is there a solution on Lustre (2.0?)
> - Others clusters have this problem?
> 
> 
> Thanks
> 
> _______________________________________________
> Lustre-discuss mailing list
> Lustre-discuss at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-discuss

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