Oh, how I love quoting directly from IBM manuals:
"If the value falls below 98%, consider increasing the size of the
database buffer pool. For larger installations, performance could
imporve significantly if your cache hit percentage is greater than 99%."
--Page 396, TSM V5.1 Administrators Guide for AIX
Memory is so cheap that you can afford to throw lots of it at it.
Roger Deschner University of Illinois at Chicago rogerd AT uic DOT edu
On Thu, 15 Jan 2004, Dwight McCann wrote:
>Roger,
>
>I really enjoyed and appreciated your response on this issue, but you've
>got me to wondering at bit. I'm running TSM 5.1.8 on Win2K with 2G
>RAM. I looked at my migration times which are about 20 minutes (so
>that's no problem) and then did the Q DB F=D and saw that my Cache Hit
>was only 96.81. You said that if it wasn't 99% it needed help. I have
>it autotuning and here are my outputs:
>
>tsm: DATAPLUS_SERVER1>q actlog begind=-2 search='expiration'
>
>Date/Time Message
>--------------------
>----------------------------------------------------------
>01/13/2004 19:19:22 ANR0984I Process 177 for EXPIRATION started in the
> BACKGROUND at 19:19:22.
>01/13/2004 19:19:22 ANR0811I Inventory client file expiration
>started as
> process 177.
>01/13/2004 19:37:58 ANR0812I Inventory file expiration process 177
>completed:
> examined 437237 objects, deleting 87348 backup
>objects, 0
> archive objects, 0 DB backup volumes, and 0
>recovery plan
> files. 0 errors were encountered.
>01/13/2004 19:37:58 ANR0987I Process 177 for EXPIRATION running in the
> BACKGROUND processed 87348 items with a
>completion state
> of SUCCESS at 19:37:58.
>01/14/2004 19:37:58 ANR0984I Process 182 for EXPIRATION started in the
> BACKGROUND at 19:37:58.
>01/14/2004 19:37:58 ANR0811I Inventory client file expiration
>started as
> process 182.
>01/14/2004 19:58:20 ANR0812I Inventory file expiration process 182
>completed:
> examined 433897 objects, deleting 104134
>backup objects,
> 0 archive objects, 0 DB backup volumes, and 0
>recovery
> plan files. 0 errors were encountered.
>01/14/2004 19:58:20 ANR0987I Process 182 for EXPIRATION running in the
> BACKGROUND processed 104134 items with a
>completion state
> of SUCCESS at 19:58:20.
>01/15/2004 09:43:06 ANR2017I Administrator DWIGHT issued command:
>QUERY ACTLOG
> begind=-2 search=expiration
>
>tsm: DATAPLUS_SERVER1>q db f=d
>
> Available Space (MB): 30,000
> Assigned Capacity (MB): 25,292
> Maximum Extension (MB): 4,708
> Maximum Reduction (MB): 19,564
> Page Size (bytes): 4,096
> Total Usable Pages: 6,474,752
> Used Pages: 1,442,366
> Pct Util: 22.3
> Max. Pct Util: 22.7
> Physical Volumes: 2
> Buffer Pool Pages: 32,768
> Total Buffer Requests: 28,394,716
> Cache Hit Pct.: 96.81
> Cache Wait Pct.: 0.00
> Backup in Progress?: No
> Type of Backup In Progress:
> Incrementals Since Last Full: 4
>Changed Since Last Backup (MB): 0.98
> Percentage Changed: 0.02
>Last Complete Backup Date/Time: 01/15/2004 05:45:26
>
>Is there something I should do to get the cache hits up to 99% even
>though I don't yet have a performance issue? I realize that my
>environment is quite small but it is about to double and I'd rather be
>proactive. TIA,
>
>--
>Dwight McCann
>Computer and Network Technologist, UCSB Info Systems & Computing
>Dwight.McCann AT isc.ucsb DOT edu, Dwight AT DwightMcCann DOT com
>http://borg.isc.ucsb.edu/dmm/ - office: 805-893-3113
>
>
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