Product

• Brisque^® 4.x
• Brisque Serve

Platform

All Brisque 4.x platforms

Operating system

IBM^® AIX^® 4.3.3

Symptoms

NFS speed and local writing to IBM disks is slow. (NFS speed is approximately 300 KB/sec, and local disk writing is approximately 7 MB/sec.)

Cause

As of Brisque 4.1 and Brisque Serve 4.021, the watermark parameters on AIX were changed to match those of Timna. IBM defaults are "0", "0", and we changed them to "9", "6".
The reason for this change was to improve foreground performance.

This change worked well with Seagate disks in old systems. But this change has a major impact on the write performance to IBM disks (6F1, 6E3, and 6E4 platforms)—up to 10 times slower.

To check your Brisque 4.1 or Brisque Serve config, type:
lsattr -El sys0|grep water
The following is displayed:
maxpout 9 HIGH water mark for pending write I/Os per file True
minpout 6 LOW water mark for pending write I/Os per file True

Solution

Changing the parameters back to the original IBM settings dramatically improves the write speed to IBM disks and NFS performance.

To reset to IBM defaults, type:
chdev -l sys0 -a maxpout=0 -a minpout=0

To reset to current Brisque/Brisque serve settings, type:
chdev -l sys0 -a maxpout=9 -a minpout=6

Note: Brisque 5.x includes this change.

Technical contact(s)

Lev Weissman

Submitted by

Lev Weissman

Date submitted

09 Sept 2004