By using this site, you agree to our updated Privacy Policy and our Terms of Use. Manage your Cookies Settings.
437,586 Members | 2,418 Online
Bytes IT Community
+ Ask a Question
Need help? Post your question and get tips & solutions from a community of 437,586 IT Pros & Developers. It's quick & easy.

db2pfchr processes and high CPU

P: n/a
Hi
DB2 8.1 FP 7a on AIX 5.2.0.

Can anyone tell me how best to reduce high CPU (and subsequent high IO)
associated with db2pfchr processes?
NUMIO_SERVERS is set to the default 3. A grep on these prefetchers
returns:

2867326 1405102 3 Feb 24 - 1460:34 db2pfchr 0
3932384 1405102 0 Feb 24 - 42:48 db2pfchr 0
5415164 1405102 0 Feb 24 - 250:57 db2pfchr 0

As machine is memory-constrained, I'm reluctant to increase bufferpool
size.

Any tips / links much appreciated.
Thanks

Apr 5 '06 #1
Share this Question
Share on Google+
1 Reply


P: n/a
Ian
pike wrote:
Hi
DB2 8.1 FP 7a on AIX 5.2.0.

Can anyone tell me how best to reduce high CPU (and subsequent high IO)
associated with db2pfchr processes?
NUMIO_SERVERS is set to the default 3. A grep on these prefetchers
returns:

2867326 1405102 3 Feb 24 - 1460:34 db2pfchr 0
3932384 1405102 0 Feb 24 - 42:48 db2pfchr 0
5415164 1405102 0 Feb 24 - 250:57 db2pfchr 0

As machine is memory-constrained, I'm reluctant to increase bufferpool
size.


The db2pfchr processes (pre-fetchers) are responsible for reading data
from disk and writing it to the bufferpool.

If you're finding that you have a lot of unread prefetch pages, that's
an indication of either having bufferpools that are too small or
prefetchsize too large for your tablespaces. If you can't increase
bufferpools...

Otherwise, there's not a lot you can do about their CPU utilization --
short of eliminating data from your database or preventing users from
running queries :-)

Apr 5 '06 #2

This discussion thread is closed

Replies have been disabled for this discussion.