[prev in list] [next in list] [prev in thread] [next in thread] 

List:       lustre-announce
Subject:    Re: [Lustre-discuss] stripe_count = 0 vagueness
From:       Andreas Dilger <adilger () clusterfs ! com>
Date:       2006-01-13 19:53:21
Message-ID: 20060113195321.GB7641 () schatzie ! adilger ! int
[Download RAW message or body]

On Jan 13, 2006  12:55 -0500, David Vasil wrote:
> Reading the man page for lmc, it says stripe_count = 0 will use the 
> "currently optimal number of stripes".  What does this mean?

Lustre currently performs best when having fewer stripes per file,
except in some specific cases.  In the vast majority of cases it
doesn't make sense to stripe files over a large number of OSTs, and
with the growth of Lustre filesystems to sometimes have hundreds of
OSTs this would be a bad "optimal" striping to pick.

> I was under the impression that using 0 as the stripe_count will make
> it stripe across all OSTs.  However, when using 0 with lmc, the following 
> INFO is given by lmc:
> 
> INFO: default stripe count (0) - will use 1 stripe(s) per file
> 
> Could someone please elaborate on what the effects are of setting the 
> stripe_count to 0?  Thanks!

Currently, setting a stripe count "0" is identical to specifying "1".
In the future this may be changed to be 2 or some other number that
gives better general-purpose performance.  If your environment does
better with some larger number of stripes you should specify that
striping explicitly in the config.  We may also add the ability to
use "-1" to mean "stripe over all OSTs", but that isn't done yet.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

_______________________________________________
Lustre-discuss mailing list
Lustre-discuss@lists.clusterfs.com
https://lists.clusterfs.com/mailman/listinfo/lustre-discuss
[prev in list] [next in list] [prev in thread] [next in thread]