ADSM-L

Re: ADSM performance

1998-10-22 14:49:08
Subject: Re: ADSM performance
From: bbullock <bbullock AT MICRON DOT COM>
Date: Thu, 22 Oct 1998 12:49:08 -0600
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
<Prev in Thread] Current Thread [Next in Thread>