SUMMARY: Low %wcache

From: Anchi Zhang (
Date: Mon Aug 21 1995 - 14:23:44 CDT

My original posting:

 On our Sparc 1000 running Solaris 2.3, patch 101318-70, and
 Oracle 7.0.16 under a heavy load, 'sar -b 30 1000' reports
 %wcache being zero most of the time whereas %rcache almost
 always 100. Is it abnormal or does it simply need tuning of
 such parameters as nhbuf, p_nbuf, and bufhwm?

Sincere thanks to (Michael K. Glass) who suggested
monitoring wcache with the DB server not running, and to (Glenn Satchell - Uniq Professional Services)
who was so kind to inquire additional info and recommend

  You might like to look at Prestoserve, which provides a non-volatile
  memory buffer for the disks and can dramatically improve write
  performance. Alternatively look at Solstice Disksuite 4.0 and the
  logging file system. Neither of these will work with raw partitions

  Also I only accelerated the partitions where the databases were. The
  default is to accelerate all UFS filesystems, but this wastes cache
  space. I had a couple of "hot" filesystems where I wanted the
  acceleration most. I especially don't think you need to presto /,
  /usr, /var or /opt since there is usually very little write activity
  on these anyway.

The hardware has been ordered and shall be installed soon.


This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:10:32 CDT