On Tue, 2003-02-04 at 16:09, Rick Smith wrote:
> I am constructing a large, high performance U320 raid0 array with XFS
> using the 2.4.20-rc1-xfs kernel and linux software raid. I am pleased with
> the performance, but it seems that when I exceed 14 disks total in the
> single raid0 array, performance becomes erratic. With 14 disks and under,
> the extents are laid out nicely in incrementing order very close to each
> other (according to xfs_bmap) and I can get very large MB/s numbers using 4
> U320 SCSI channels and 73GB disks. However, with 15+ disks, I am seeing
> large, erratic gaps in the extents, which is seriously affecting read/write
> performance. I don't exceed 5 drives per channel, and the problem seems to
> exist no matter what SCSI configuration that I use. I have tried various
> numbers of channels and disks per channel, but the problem remains when I
> exceed 14 disks. Currently the read performance for 15 disks is about half
> the read performance for 14 disks in the array.
> Other filesystems tested (reiserfs and ext2/3) do not seem to suffer
> from this problem, but they also don't produce the awesome speed that the
> XFS filesystem does.
> I plan on experimenting with the latest 2.4 and 2.5 versions of the XFS
> kernel as soon as I can get a good copy from CVS.
> Any help is appreciated. Thanks.
Sounds like you need to play with mkfs options on XFS. Can you send
the output of xfs_info /mnt where /mnt is the mounted filesystem.
Steve Lord voice: +1-651-683-3511
Principal Engineer, Filesystem Software email: lord@xxxxxxx