That parameter is set in the dsmserv.opt file. Here is the somewhat garbled
text from the ADSM tuning guide found at :
http://www.storage.ibm.com/software/adsm/pfguide/tgv31mst.htm#HDRDUST
Ben
_________________________________________
BUFPoolsize
The database buffer pool provides cache storage, which allows database pages
to remain in memory for longer periods of time. When database pages
remain in cache, the server can make continuous updates to the pages without
requiring I/O operations to external storage. While a database buffer pool
can improve server performance, it will also require more virtual memory.
An optimal setting for the database buffer pool is one in which the cache
hit percentage is greater than or equal to 98%. To check the cache hit
percentage,
use the query db format=detail Increasing the BUFPoolsize parameter can
improve the performance of many ADSM server functions such as multi-client
backup, storage pool migration, storage pool backup, expiration processing
and move data. If the cache hit percentage is lower than 99%, increase the
size
of the BUFPoolsize parameter in the DSMSE RV.OPT file. (It is necessary to
shutdown and restart the server, for any change to take effect.) For most
servers, we recommend starting with a value of 32768, which equals 8192
database pages. If you have enough memory, increase in 1MB increments. A
cache hit percentage greater than 99% is an indication that the proper
BUFPoolsize has been reached. However, continuing to raise BUFPoolsize
beyond
that level can be very helpful. While increasing BUFPoolsize, care must be
taken not to cause paging in the virtual memory system. Monitor system
memory
usage to check for any increased paging after the BUFPoolsize change. (Use
the RESET BUFP command to reset the cache hit statistics.) With
v2.1.0.6/v.2.1.5.6 and above, the default is 2048KB. For previous releases,
the default is 512KB. With v2.1.0.6 and above (v2.1.5.6 and above for AIX
v4.1.4).
Recommendations for AIX, HP, Sun, NT, OS/2 Servers
System Memory (MB)
Recommended Buffer Pool
Size (MB)
Recommended Buffer
Pool
Size (KB)
32
2
2048
48
3
3072
64
4
4096
96
9
9216
128
14
14336
160
20
20480
256
32
32768
512
64
65536
1024
128
131072
-----Original Message-----
From: Ken Chamberlain [SMTP:ken.chamberlain AT UTORONTO DOT CA]
Sent: Thursday, October 22, 1998 9:14 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: ADSM performance
Another question...
I've seen recommendations in this list forum advising ADSM
administrators to
run the ADSM server with a large enough buffer pool so that cache
hit
percentage is about 98%. When I issue "q db f=d" it reports:
Buffer Pool Pages: 128
Total Buffer Requests: 354,376,322
Cache Hit Pct.: 89.48
Cache Wait Pct.: 0.00
So I guess we're a little low on buffer pool, and I've noticed daily
copy
pool processing and disk to tape migration is taking longer and
longer.
I've asked our unix support guy to look into upping buffer pool, but
he's
come back with "How?". So my question is: How/where do we specify
buffer
pool size? "q db f=d" reports it at 128 pages but where do we
specify 128
pages? This must be a default.
Ken Chamberlain
University of Toronto
Phone:(416) 978-1582
Fax: (416) 971-2085
E-mail: ken.chamberlain AT utoronto DOT ca
|