On Wed, Aug 10, 2005 at 12:43:39PM -0400, Matt Clausen wrote:
> Yet when I do a backup to disk, I see decent performance 
> on one stream (about 8,000KB/s or so) but the other streams will drop to 
> around 300-500KB/s.
> 
> NUMBER_DATA_BUFFERS = 16
> NUMBER_DATA_BUFFERS_DISK = 16
> 
> SIZE_DATA_BUFFERS = 262144
> SIZE_DATA_BUFFERS_DISK = 1048576
> 
> and I see this performance on both the master server disk pool AND a 
> media server disk pool. The master server is a VxVM concat volume set of 
> 3x73GB 10,000RPM disks and the media server is an external raid 5 volume 
> of 16x250GB SATA disks. 

I don't believe you're going to get good performance on a 16 member
RAID5 set of SATA disk.  You should get better with a pair of 8 member
raid sets, but SATA is not fast disk and large raid 5 sets kill you on
write performance.  If you're stuck with the SATA drives, configure them
as 3 4+1 RAID5 sets and use the 16th member as a hot spare.  You'll have
3TB of disk staging instead of about 3.8TB but it will perform a lot
better.

-- 
Ed Wilts, Mounds View, MN, USA
mailto:ewilts AT ewilts DOT org