IDS Forum

Re: IDS BUFFER POLL CONFIG

Posted By: Richard Kofler
Date: Friday, 8 January 2010, at 9:20 a.m.

In Response To: IDS BUFFER POLL CONFIG (HELDER JESUS)

HELDER JESUS schrieb:
> Good afternoon
>
> My Name is Helder Jesus.
> I was wondering if there was a formula to configure BUFFERPOOL and SHMVIRTSIZE
> correctly regarding the machine specifications of memory and cpu capabilities
>
> Thanks in advance seeing that this is my first post!
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

Hi,

a general formula is not an easy thing.
It depends on so many influencing factors; to name a few:
- dedicated DB server or other apps on the same machine
- one IDS instance or more than one
- how big is the working set of your databases
- OLTP workload or DSS workload or *shudders* a mix

In short:
Bufferpool(s)
it is a good thing to have high read cache rate (onstat -p)
high == better than 98.5%, best 99+%, IFF your workload is
read bound, which is mostly the case.
It is a good thing to have isolation, i.e. to have the most active
and read bound table(s) / index(es) in a separate BUFFERPOOL by
creating dbspaces with a different pagesize and putting (only!) those
DB objects there.
shmvirtsize, shmadd
It is a good thing to have only one V-segment. Make SHMVIRTSIZE
big enough to cover all, if you see more than one V-segment in
onstat -g seg output.
For hash joins is it a good thing to have the hash table incore
to avoid I/O.
It is a good thing to have enough V-seg size to use PDQ memory
(or Memory Grant Manager - MGM - managed memory)
It is nice to have enough PDQ mem to do index(re-)build sorts
incore, as with each and every sort. So you reduce I/O
on dbspaces in the DBSPACETEMP list.

But all depends very much on IDS version

[ please ALWAYS - in EVERY new post - give IDS version

seen in 'onstat -' output and OS type and version and

in every answer please quote the relevant parts of the posting

or thread. So those, who use a news- or mailreader ( == we :) )

have the context ]

and it depends on HW type (amount of memory, DAS, SAN or NAS disks
SSDs or no SSDs), workload and performance expectations.

dic_k
--
Richard Kofler
SOLID STATE EDV
Dienstleistungen GmbH
Vienna/Austria/Europe

Messages In This Thread

• IDS BUFFER POLL CONFIG *NM*
  HELDER JESUS -- Friday, 8 January 2010, at 8:20 a.m.
  • IDS BUFFER POLL CONFIG
    HELDER JESUS -- Friday, 8 January 2010, at 8:26 a.m.
    • Re: IDS BUFFER POLL CONFIG
      Art Kagel -- Friday, 8 January 2010, at 8:52 a.m.
    • Re: *** SPAM *** IDS BUFFER POLL CONFIG
      Alexandre Marini -- Friday, 8 January 2010, at 8:59 a.m.
    • Re: IDS BUFFER POLL CONFIG
      Richard Kofler -- Friday, 8 January 2010, at 9:20 a.m.
      • Re: IDS BUFFER POLL CONFIG
        HELDER JESUS -- Friday, 8 January 2010, at 9:25 a.m.
        • Re: IDS BUFFER POLL CONFIG
          Art Kagel -- Friday, 8 January 2010, at 9:30 a.m.
        • Re: IDS BUFFER POLL CONFIG
          Alexandre Marini -- Friday, 8 January 2010, at 9:41 a.m.
          • Re: IDS BUFFER POLL CONFIG
            Alexandre Marini -- Friday, 8 January 2010, at 9:52 a.m.

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