NUMAIOVPS and KAIOON

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? 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 ? 3. Also can someone please explain very breifly relationship between nfile kernal parameter(HP-UX) & NUMAIOVPS Any tip for NUMAIOVPS tuning would be highly appreciated? TIA --------------------------------- Get the name you always wanted with the new y7mail email address.

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!! > > >

Hi, you can have "mixed chunks", i.e. some on raw devices utilizing KAIO and some in file system files (aka cooked files). AIO-VPs are used for I/O to/from cooked files. So to be more precise it should say "2 * Number of cooked file chunks ,,,". If all your chunks are on raw devices, then have at least one AIOVP, if for nothing else then for writing to the message log. Another use may be if some temporary files for sorting get created in the file system (so you may want to have two AIO-VPs). But whether file system files are used for temp files again depends on whether you have enough temp dbspaces (on raw devices) or not, and on a possible setting of PSORT_DBTEMP... (env variable with a similar name at least) ... So in general the rule is correct, but one could argue a bit simplistic. As usual real life is a bit more complicated ... :) Regards, Martin -- Martin Fuerderer IBM Informix Development Munich, Germany Information Management IBM Deutschland Entwicklung GmbH Chairman of the Supervisory Board: Martin Jetter Board of Management: Herbert Kircher Corporate Seat: Boeblingen, Germany Reg.-Gericht: Amtsgericht Stuttgart, HRB 243294 ids-bounces@iiug.org wrote on 27.03.2008 20:45:15: > 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? > 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 ? > 3. Also can someone please explain very breifly relationship between nfile > kernal parameter(HP-UX) & NUMAIOVPS > > 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!!

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.

You're welcome. :) Also (this crossed my mind too late yesterday), you may want to use the output of several onstat commands to determine whether you have too many AIO-VPs: onstat -g glo onstat -g iof onstat -g iog onstat -g iov Regards, Martin -- Martin Fuerderer IBM Informix Development Munich, Germany Information Management IBM Deutschland Entwicklung GmbH Chairman of the Supervisory Board: Martin Jetter Board of Management: Herbert Kircher Corporate Seat: Boeblingen, Germany Reg.-Gericht: Amtsgericht Stuttgart, HRB 243294 ids-bounces@iiug.org wrote on 28.03.2008 06:48:29: > 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. > > > ******************************************************************************* > 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!!

3. Relationship between nfile kernal parameter(HP-UX) & NUMAIOVPS AIOVP's grab a file handle on each chunk they need to access(and they never release them until you down the instance). Over time this can build up to a situation where every AIOVP has a file handle on every chunk. To accomodate this make sure your nfile parameter exceeds (AIOVP's * chunks). Running out of nfile resources on an HP-UX system is ugly. If your using AIOVP's instead of KAIO, you definately need to keep this limit in mind.

That's exactly I want to know in terms of nfile and AIOVPS. Thanks Dave, Art and Martin for your help. DAVE GRIFFEN <dgriffen@finishline.com> wrote: 3. Relationship between nfile kernal parameter(HP-UX) & NUMAIOVPS AIOVP's grab a file handle on each chunk they need to access(and they never release them until you down the instance). Over time this can build up to a situation where every AIOVP has a file handle on every chunk. To accomodate this make sure your nfile parameter exceeds (AIOVP's * chunks). Running out of nfile resources on an HP-UX system is ugly. If your using AIOVP's instead of KAIO, you definately need to keep this limit in mind. ******************************************************************************* 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.