On pon, 21 mar 2016 at 09:24:02 +0000, Dilger, Andreas wrote: > On 2016/03/18, 12:52, "Kurt Strosahl" <[email protected]> wrote: > >Good Afternoon, > > > > I'm experimenting with ost configurations geared more towards small > >files and operations on those small files (like source code, and > >compiling), and I was wondering about changing the stripe size so that > >small files fit more efficiently on an ost. I believe that would be the > >--param lov.stripesize=XX option for mkfs.lustre, is that correct? And > >is there a lower limit that I should know about? > > Just to clarify, the stripe size for Lustre is not a property of the OST, > but rather a property of each file. The OST itself allocates space > internally as it sees fit. For ldiskfs space allocation is done in units > of 4KB blocks managed in extents, while ZFS has variable block sizes (512 > bytes up to 1MB or more, but only one block size per file) managed in a > tree. In both cases, if a file is sparse then no blocks are allocated for > the holes in the file. > > As for the minimum stripe size, this is 64KB, since it isn't possible to > have a stripe size below the PAGE_SIZE on the client, and some > architectures (e.g. IA64, PowerPC, Alpha) allowed 64KB PAGE_SIZE. > > For small files, the stripe_size parameter is virtually meaningless, since > the data will never exceed a single stripe in size. What is much more > important is to use a stripe_count=1, so that the client doesn't have to > query multiple OSTs to determine the file size, timestamps, and other > attributes.
Andreas, default stripe size is 1MB. Is there a reason for that? P -- Pawel Dziekonski <[email protected]> Wroclaw Centre for Networking & Supercomputing, HPC Department phone: +48 71 320 37 39, fax: +48 71 322 57 97, http://www.wcss.pl _______________________________________________ lustre-discuss mailing list [email protected] http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
