Bufferpool thresholds

K T

Bufferpool thresholds

Hi All,
In our DB2 system (z/os v7.1) , looking thru the TMON ,system snapshot
under the collection analysis screen. I am seeing that for a bufferpool
the IMW ( Immediate write) threshold has been reached a certain times,
during the same period the VDWT has also been reached , the count of the
VWDT is higher. I want to know if this clearly shows a buffer shortage
or my thresholds are set too low that they are being reached too often.
I cannot change my IMW . any assistance will be helpful. I know the data
is less or insufficient. Here is what I see. This pool has tables only
belonging to one particular application

BP2
===
IMW REACHED 2 TIMES
VDWT REACHED 102 TIMES
BP UTILIZATION 16.2
# OF BUFFERS 30000
ALLOCATED BUFFERS 4875

AT THE SAME TIME

BP11
====
IMW REACHED 0
DVWT REACHED 246
BP UTILIZATION 9.7
# BUFFERS 20000
ALLOCATED BUFFERS 1947

The BP11 pool holds all the indexes for tables that are in BP2. The
above snapshot is for a minute , and when I go backwards in time there
are other times too when the limit has been reached , though the
numbers are different but the pattern seems to be the same.

TIA
-KT

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Joel Goldstein

Re: Bufferpool thresholds
(in response to K T)
If you have not hit DMTH ignore this, it's normal operation.
If a hot page is in the pool at a second checkpoint, this can occur. If a
page is scheduled to be written,
and is requested by another application, it's taken off the write Q, used,
and then DB2 issues a Synch write for it, but triggers
the IWTH because it's a synch write.

You should also see a much higher number of hits for vdwqt than DWQT.

Regards,
Joel

----- Original Message -----
From: "Trivedi, Kaushal" <[login to unmask email]>
Newsgroups: bit.listserv.db2-l
To: <[login to unmask email]>
Sent: Tuesday, December 20, 2005 1:23 PM
Subject: [DB2-L] Bufferpool thresholds



Hi All,
In our DB2 system (z/os v7.1) , looking thru the TMON ,system snapshot
under the collection analysis screen. I am seeing that for a bufferpool
the IMW ( Immediate write) threshold has been reached a certain times,
during the same period the VDWT has also been reached , the count of the
VWDT is higher. I want to know if this clearly shows a buffer shortage
or my thresholds are set too low that they are being reached too often.
I cannot change my IMW . any assistance will be helpful. I know the data
is less or insufficient. Here is what I see. This pool has tables only
belonging to one particular application

BP2
===
IMW REACHED 2 TIMES
VDWT REACHED 102 TIMES
BP UTILIZATION 16.2
# OF BUFFERS 30000
ALLOCATED BUFFERS 4875

AT THE SAME TIME

BP11
====
IMW REACHED 0
DVWT REACHED 246
BP UTILIZATION 9.7
# BUFFERS 20000
ALLOCATED BUFFERS 1947

The BP11 pool holds all the indexes for tables that are in BP2. The
above snapshot is for a minute , and when I go backwards in time there
are other times too when the limit has been reached , though the
numbers are different but the pattern seems to be the same.

TIA
-KT

-----------------------------------------
Use of email is inherently insecure. Confidential information,
including account information, and personally identifiable information,
should not be transmitted via email, or email attachment. In no event
shall Citizens or any of its affiliates accept any responsibility for
the loss, use or misuse of any information including confidential
information, which is sent to Citizens or its affiliates via email, or
email attachment. Citizens does not guarantee the accuracy of any email
or email attachment, that an email will be received by Citizens or that
Citizens will respond to any email.

This email message is confidential and/or privileged. It is to be used
by the intended recipient only. Use of the information contained in
this email by anyone other than the intended recipient is strictly
prohibited. If you have received this message in error, please notify
the sender immediately and promptly destroy any record of this email.


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