Bufferpool Allocation

Tim R - CNF Ohling

Bufferpool Allocation
What are the potential issues with a bufferpool that is allocated more space
than it really needs to handle the objects assigned to it?

The first one that comes to mind is that the space isn't "available" for
other pools, but are there others that we need to be concerned about?

TIA

Tim

Joel Goldstein

Re: Bufferpool Allocation
(in response to Tim R - CNF Ohling)
Message text written by DB2 Data Base Discussion List
>What are the potential issues with a bufferpool that is allocated more
space
than it really needs to handle the objects assigned to it?

The first one that comes to mind is that the space isn't "available" for
other pools, but are there others that we need to be concerned about?
TIA
Tim<
++++++++++++++++++++++++++++++++++
The only real issue is wasting memory that could be used effectively
someplace else. The hard part is determining that the pool is too
large, and what the best smaller size would be.
Regards,
Joel
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Richard Humphris

Re: Bufferpool Allocation
(in response to Joel Goldstein)
Only problem could be if your processor doesn't have enough storage to
support your buffer pools. If your buffer pools aren't seeing a lot of MVS
paging, then there isn't a penality. Otherwise, you may want to size it
better or get more real storage.

IBM uses a hash implementation to find pages in the buffer pool, so CPU time
used to find things in the buffer pool remains the same reguardless of the
size of the buffer pool (very nice). In fact, if the increase in the buffer
pool will avoid more I/O you'll probably see a reduction in CPU time;
because some CPU time is required to handle I/O.

> -----Original Message-----
> From: Ohling, Tim R - CNF [SMTP:[login to unmask email]
> Sent: Thursday, October 07, 1999 10:57 AM
> To: [login to unmask email]
> Subject: Bufferpool Allocation
>
> What are the potential issues with a bufferpool that is allocated more
> space
> than it really needs to handle the objects assigned to it?
>
> The first one that comes to mind is that the space isn't "available" for
> other pools, but are there others that we need to be concerned about?
>
> TIA
>
> Tim