Re: Total Virtual Pool Size

Leslie Pendlebury-Bowe

Re: Total Virtual Pool Size
(in response to Roger Miller)
Andy
I have the calculations infront of me as to how to size your DBM1
Address space (inludes the Virtual Pools).

It is interesting when you do the calculations as to what you have to
play with for your Virtual Pools...

Leslie Pendlebury-Bowe
DB2 SAP OS390
DB2 UDB Certified etc


______________________________ Reply Separator _________________________________
Subject: Total Virtual Pool Size
Author: Andy Hunt <[login to unmask email]> at Internet
Date: 12/14/99 3:24 PM


How big are your Virtual Pools ?

Ive heard from an IBM source that problems can occur if you allocate > 500-600
Mb total and that it is recommended total virtual pool allocation is below this
(futher expansion should use hiperpools). Ive trawled through the DB2 Storage
Informational APARs II04309(II10817) but cant find anything that indicates this
problem/strategy.

Does anybody have total virtual pool allocation > 500-600Mb ? If so, whats their
size and have you experienced any problems (at V5 or V6)?
Has anybody seen an APAR containing this recommendation ?

Kind Regards,
Andy Hunt - Scottish And Southern Energy


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Andy Hunt

Total Virtual Pool Size
How big are your Virtual Pools ?

Ive heard from an IBM source that problems can occur if you allocate > 500-600
Mb total and that it is recommended total virtual pool allocation is below this
(futher expansion should use hiperpools). Ive trawled through the DB2 Storage
Informational APARs II04309(II10817) but cant find anything that indicates this
problem/strategy.

Does anybody have total virtual pool allocation > 500-600Mb ? If so, whats their
size and have you experienced any problems (at V5 or V6)?
Has anybody seen an APAR containing this recommendation ?

Kind Regards,
Andy Hunt - Scottish And Southern Energy


**********************************************************************
The information in this E-Mail is confidential and may be legally
privileged. It may not represent the views of Scottish and Southern
Energy plc.
It is intended solely for the addressees. Access to this E-Mail by
anyone else is unauthorised. If you are not the intended recipient,
any disclosure, copying, distribution or any action taken or omitted
to be taken in reliance on it, is prohibited and may be unlawful.
Any unauthorised recipient should advise the sender immediately of
the error in transmission.

Scottish Hydro-Electric and Southern Electric are trading names of
Scottish and Southern Energy Group
**********************************************************************



Adrian Savory

Re: Total Virtual Pool Size
(in response to Andy Hunt)
Andy,

I've worked at a site where we had a total virtual pool size of 720Mb and we did
experience storage problems (this was an SAP site though - SAP is very hungry on
the storage side). We did a number of things to reduce storage requirements, one
of which was to reduce the virtual pools to 400Mb and back them with big
hiperpools. The hiperpools coped with the load extremely well, so much so that
our response times actually dropped.

There are many other things that will affect your storage requirements,
specifically:

EDMPOOL
RID POOL
DSMAX
CTHREAD
Use of compression
Use of dynamic SQL cache
Implementation of various storage fixes e.g. storage cushion, CONSTOR ZPARM

Hope this helps,

Adrian Savory
ACSIS Ltd






Andy Hunt <[login to unmask email]> on 14/12/99 15:24:09

Please respond to DB2 Data Base Discussion List <[login to unmask email]>

To: [login to unmask email]
cc: (bcc: Adrian Savory/ZI/England/Zurich)

Subject: Total Virtual Pool Size



How big are your Virtual Pools ?

Ive heard from an IBM source that problems can occur if you allocate > 500-600
Mb total and that it is recommended total virtual pool allocation is below this
(futher expansion should use hiperpools). Ive trawled through the DB2 Storage
Informational APARs II04309(II10817) but cant find anything that indicates this
problem/strategy.

Does anybody have total virtual pool allocation > 500-600Mb ? If so, whats their
size and have you experienced any problems (at V5 or V6)?
Has anybody seen an APAR containing this recommendation ?

Kind Regards,
Andy Hunt - Scottish And Southern Energy


**********************************************************************
The information in this E-Mail is confidential and may be legally
privileged. It may not represent the views of Scottish and Southern
Energy plc.
It is intended solely for the addressees. Access to this E-Mail by
anyone else is unauthorised. If you are not the intended recipient,
any disclosure, copying, distribution or any action taken or omitted
to be taken in reliance on it, is prohibited and may be unlawful.
Any unauthorised recipient should advise the sender immediately of
the error in transmission.

Scottish Hydro-Electric and Southern Electric are trading names of
Scottish and Southern Energy Group
**********************************************************************








Roger Miller

Re: Total Virtual Pool Size
(in response to Adrian Savory)
There are very few absolutes about the sizes. With only 2 GB in the
address space
as one absolute, some customers who have lots of dynamic statement cache or
very large numbers of threads (e.g. query parallelism) found that they
needed
to reduce their virtual buffer pool sizes.

If you do have large pools and large numbers of users, then it's time to
start
watching out for the 2 GB address space limit.

Roger Miller