IDS Forum

Re: NUMAIOVPS and KAIOON

Posted By: H.G
Date: Friday, 28 March 2008, at 1:48 a.m.

In Response To: Re: NUMAIOVPS and KAIOON (Art S. Kagel (Oninit))

Thanks Art & Martin for your prompt response very useful tips. Appreciated.

"Art S. Kagel (Oninit)" <art@oninit.com> wrote: H.G wrote:
> Greeting all,
>
> My understanding is in IDS 10, System Admin guide recommends NUMAIOVPS = 2 *
> No of Chunks or 6 whichever is greater.
>
> Questions:
>
> 1. Is it also valid for IDS 9.40.FC4?
>

Yes, but ONLY if you do not have KAIO turned on or if your chunks are
COOKED devices or filesystem files (unless your IDS version and OS
support O_DIRECT IO and you have enabled that). If you are using RAW
chunks and KAIO (or COOKED chunks with O_DIRECT) you need only a few AIO
VPs. The actual number varies depending on server load, I've seen sites
that were running happy with only one AIO VP and others that needed as
many as six with KAIO working for all chunks. (Note that IDS 9.40 does
not support O_DIRECT IO, so that doesn't help you at all. So, if you
are using COOKED chunks, you will have to follow those recommendations.)

> 2. Is it also valid if KAIOON is enable? Is there any overhead in terms of
> server performance if we follow above recommendation (2 * No. of chunks)
when
> KAIOON is enable ?
>

If KAIOON is set on HPUX (or KAIOOFF is NOT set on other platforms) and
the OS kernel is properly tuned for KAIO, and all of your chunks are RAW
devices, then you will not need many AIO VPs. If your chunks are COOKED
(ie block devices or filesystem files) then you will still need 2 AIO
VPs for each COOKED chunk plus a few for text file IO like the message log.

The overhead of too many AIO VPs is the same as having that many tasks
that are asleep forever and not doing anything. On HPUX they will be
taking up lots of swap space, on other UNIX's the swap footprint will be
less. If swap space is tight, that can be significant and can prevent
other tasks from starting up. Otherwise there will be little impact.

> 3. Also can someone please explain very breifly relationship between nfile
> kernal parameter(HP-UX) & NUMAIOVPS
>

Don't know that there is one. IB nfiles are the number of concurrent
open files per process. This will affect the engine's ability to open
disk chunks, shared libraries, and message log files. If it is set too
low the engine will not start up or will crash at some point.

Art S. Kagel
Oninit

> Any tip for NUMAIOVPS tuning would be highly appreciated?
>
> TIA
>
> ---------------------------------
> Get the name you always wanted with the new y7mail email address.
>
>
>
*******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
> See you at the IIUG Informix 2008 Conference
> The Power Conference for Informix Professionals
> April 27 - 30, 2008 Marriott Overland Park (Kansas City), Kansas
> http://www.iiug.org/conf
> Registration Now Open!!
>
>
>

*******************************************************************************
Forum Note: Use "Reply" to post a response in the discussion forum.

See you at the IIUG Informix 2008 Conference
The Power Conference for Informix Professionals
April 27 - 30, 2008 Marriott Overland Park (Kansas City), Kansas
http://www.iiug.org/conf
Registration Now Open!!

---------------------------------
Get the name you always wanted with the new y7mail email address.

Messages In This Thread

• NUMAIOVPS and KAIOON
  H.G -- Thursday, 27 March 2008, at 3:45 p.m.
  • Re: NUMAIOVPS and KAIOON
    Art S. Kagel (Oninit) -- Thursday, 27 March 2008, at 4:30 p.m.
    • Re: NUMAIOVPS and KAIOON
      H.G -- Friday, 28 March 2008, at 1:48 a.m.
      • Re: NUMAIOVPS and KAIOON
        Martin Fuerderer -- Friday, 28 March 2008, at 4:35 a.m.
  • Re: NUMAIOVPS and KAIOON
    Martin Fuerderer -- Thursday, 27 March 2008, at 5:00 p.m.
  • Re: NUMAIOVPS and KAIOON
    DAVE GRIFFEN -- Friday, 28 March 2008, at 4:25 p.m.
    • Re: NUMAIOVPS and KAIOON
      H.G -- Friday, 28 March 2008, at 5:28 p.m.

IDS Forum is maintained by Administrator with WebBBS 5.12.