Informix Chunk Size - 1 big or manysmaller
This question was posted by someone on the list serve for the product I work with, but there hasnât been much of a response. I was hoping someone could answer the below as Iâm interested in this as well. (note that this will relate to a SLES 11x64 IDS 11.50 box) I'm looking for opinions (facts acceptable too). We are in the hardware and disk layout phase of preparing for CX on Linux. I look at our current system and see 5 chunks for our cars database dbspace. They are each 2 GB for a total of 10GB. My question is: Should I set the new server up with one big chunk (~20GB) or break it up into more smaller chunks? Research: I have been searching for an answer to this question and do not find much guidance. I found that there used to be a 2GB size limit on a single chunk until Informix 9.4. There also used to be a limit on the number of chunks around 4000. I think the new limit on the number of chunks is 32766. I found one page that said with multiple chunks there are multiple threads to flush changes to disk so it takes less time to flush changes. There is an SAP tuning page that states that the ideal number of chunks for a dbspace is 1. Other than that don't have too much info. I would love to hear any opinions (or facts). Sean Jonathon Wyza CX & CBORD System Administrator CX Programmer/Analyst Administrative Computing Bethel College (574)-257-3381 AIM: Iamwyza jonathon.wyza@bethelcollege.edu<mailto:jonathon.wyza@bethelcollege.edu> ============================== SLES 10x32 SP2 & IDS 10.00.UC9 " I would love to change the world, but they won't give me the source code." -- Unknown
When I tested changing to a large chuck size instead of smaller ones, the larger ones always was slower. I kept the smaller chunk sizes and controlled the fragmentation to achieve the best performance. Lennie On Wed, Mar 31, 2010 at 2:04 PM, Wyza, Jonathon <wyzaj@bethelcollege.edu>wrote: > This question was posted by someone on the list serve for the product I > work > with, but there hasnt been much of a response. I was hoping someone could > answer the below as Im interested in this as well. (note that this will > relate to a SLES 11x64 IDS 11.50 box) > > I'm looking for opinions (facts acceptable too). > > We are in the hardware and disk layout phase of preparing for CX on Linux. > I > look at our current system and see 5 chunks for our cars database dbspace. > They are each 2 GB for a total of 10GB. > > My question is: > Should I set the new server up with one big chunk (~20GB) or break it up > into > more smaller chunks? > > Research: > I have been searching for an answer to this question and do not find much > guidance. I found that there used to be a 2GB size limit on a single chunk > until Informix 9.4. There also used to be a limit on the number of chunks > around 4000. I think the new limit on the number of chunks is 32766. I > found > one page that said with multiple chunks there are multiple threads to flush > changes to disk so it takes less time to flush changes. There is an SAP > tuning > page that states that the ideal number of chunks for a dbspace is 1. Other > than that don't have too much info. > > I would love to hear any opinions (or facts). > > Sean > > Jonathon Wyza > CX & CBORD System Administrator > CX Programmer/Analyst > Administrative Computing > Bethel College > (574)-257-3381 > AIM: Iamwyza > jonathon.wyza@bethelcollege.edu<mailto:jonathon.wyza@bethelcollege.edu> > ============================== > SLES 10x32 SP2 & IDS 10.00.UC9 > > " I would love to change the world, but they won't give me the source > code." > -- Unknown > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --000325559a92e16f5704831d7cea
It is a balance, as in most things. At checkpoint time the engine assigns chunks to CLEANER threads so the more chunks you have the more processes you will have flushing your data to disk in parallel to minimize checkpoint time and impact on the system. Longer checkpoints also may mean more data at risk or longer recovery times if the server crashes during a checkpoint. On the other hand, the fewer chunks you have the easier it is to manage the server. Tradeoffs and no hard rules. Art Art S. Kagel Advanced DataTools (www.advancedatatools.com) IIUG Board of Directors (art@iiug.org) See you at the 2010 IIUG Informix Conference April 25-28, 2010 Overland Park (Kansas City), KS www.iiug.org/conf Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on my employer, Advanced DataTools, the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves. On Wed, Mar 31, 2010 at 3:04 PM, Wyza, Jonathon <wyzaj@bethelcollege.edu>wrote: > This question was posted by someone on the list serve for the product I > work > with, but there hasnt been much of a response. I was hoping someone could > answer the below as Im interested in this as well. (note that this will > relate to a SLES 11x64 IDS 11.50 box) > > I'm looking for opinions (facts acceptable too). > > We are in the hardware and disk layout phase of preparing for CX on Linux. > I > look at our current system and see 5 chunks for our cars database dbspace. > They are each 2 GB for a total of 10GB. > > My question is: > Should I set the new server up with one big chunk (~20GB) or break it up > into > more smaller chunks? > > Research: > I have been searching for an answer to this question and do not find much > guidance. I found that there used to be a 2GB size limit on a single chunk > until Informix 9.4. There also used to be a limit on the number of chunks > around 4000. I think the new limit on the number of chunks is 32766. I > found > one page that said with multiple chunks there are multiple threads to flush > changes to disk so it takes less time to flush changes. There is an SAP > tuning > page that states that the ideal number of chunks for a dbspace is 1. Other > than that don't have too much info. > > I would love to hear any opinions (or facts). > > Sean > > Jonathon Wyza > CX & CBORD System Administrator > CX Programmer/Analyst > Administrative Computing > Bethel College > (574)-257-3381 > AIM: Iamwyza > jonathon.wyza@bethelcollege.edu<mailto:jonathon.wyza@bethelcollege.edu> > ============================== > SLES 10x32 SP2 & IDS 10.00.UC9 > > " I would love to change the world, but they won't give me the source > code." > -- Unknown > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --00151748dd325cc9fc048322a139
Wouldn't IO speed would ultimately determine the flush time? IF 5 thread/chunk writing to the same disk or striped disk, wouldn't it be the same as 1 thread/chunk? I believe unless the chunk are in different disk it wouldn't make any differece. Paul -----Original Message----- From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of Art Kagel Sent: Thursday, 1 April 2010 12:18 PM To: ids@iiug.org Subject: Re: Informix Chunk Size - 1 big or manysmaller [19477] It is a balance, as in most things. At checkpoint time the engine assigns chunks to CLEANER threads so the more chunks you have the more processes you will have flushing your data to disk in parallel to minimize checkpoint time and impact on the system. Longer checkpoints also may mean more data at risk or longer recovery times if the server crashes during a checkpoint. On the other hand, the fewer chunks you have the easier it is to manage the server. Tradeoffs and no hard rules. Art Art S. Kagel Advanced DataTools (www.advancedatatools.com) IIUG Board of Directors (art@iiug.org) See you at the 2010 IIUG Informix Conference April 25-28, 2010 Overland Park (Kansas City), KS www.iiug.org/conf Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on my employer, Advanced DataTools, the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves. On Wed, Mar 31, 2010 at 3:04 PM, Wyza, Jonathon <wyzaj@bethelcollege.edu>wrote: > This question was posted by someone on the list serve for the product > I work with, but there hasn't been much of a response. I was hoping > someone could answer the below as I'm interested in this as well. > (note that this will relate to a SLES 11x64 IDS 11.50 box) > > I'm looking for opinions (facts acceptable too). > > We are in the hardware and disk layout phase of preparing for CX on Linux. > I > look at our current system and see 5 chunks for our cars database dbspace. > They are each 2 GB for a total of 10GB. > > My question is: > Should I set the new server up with one big chunk (~20GB) or break it > up into more smaller chunks? > > Research: > I have been searching for an answer to this question and do not find > much guidance. I found that there used to be a 2GB size limit on a > single chunk until Informix 9.4. There also used to be a limit on the > number of chunks around 4000. I think the new limit on the number of > chunks is 32766. I found one page that said with multiple chunks there > are multiple threads to flush changes to disk so it takes less time to > flush changes. There is an SAP tuning page that states that the ideal > number of chunks for a dbspace is 1. Other than that don't have too > much info. > > I would love to hear any opinions (or facts). > > Sean > > Jonathon Wyza > CX & CBORD System Administrator > CX Programmer/Analyst > Administrative Computing > Bethel College > (574)-257-3381 > AIM: Iamwyza > jonathon.wyza@bethelcollege.edu<mailto:jonathon.wyza@bethelcollege.edu > > > ============================== > SLES 10x32 SP2 & IDS 10.00.UC9 > > " I would love to change the world, but they won't give me the source > code." > -- Unknown > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --00151748dd325cc9fc048322a139 ******************************************************************************* Forum Note: Use "Reply" to post a response in the discussion forum.
If you are talking about multiple chunks on a single spindle, you may be correct, however, if the chunks are allocated from a RAID array located on a SAN with extensive non-volatile cache memory, then you can absolutely push more data down to it than a single thread can handle. And again, how many threads and how much data will choke the cache and revert to slower behavior, will depend on your configuration, so YMMV and back to the trade-offs. Art Art S. Kagel Advanced DataTools (www.advancedatatools.com) IIUG Board of Directors (art@iiug.org) See you at the 2010 IIUG Informix Conference April 25-28, 2010 Overland Park (Kansas City), KS www.iiug.org/conf Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on my employer, Advanced DataTools, the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves. On Wed, Mar 31, 2010 at 9:31 PM, Chin, Paul (TSG-OSDO) <pchin@hp.com> wrote: > Wouldn't IO speed would ultimately determine the flush time? IF 5 > thread/chunk > writing to the same disk or striped disk, wouldn't it be the same as 1 > thread/chunk? > > I believe unless the chunk are in different disk it wouldn't make any > differece. > > Paul > > -----Original Message----- > From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of Art > Kagel > Sent: Thursday, 1 April 2010 12:18 PM > To: ids@iiug.org > Subject: Re: Informix Chunk Size - 1 big or manysmaller [19477] > > It is a balance, as in most things. At checkpoint time the engine assigns > chunks to CLEANER threads so the more chunks you have the more processes > you > will have flushing your data to disk in parallel to minimize checkpoint > time > and impact on the system. Longer checkpoints also may mean more data at > risk > or longer recovery times if the server crashes during a checkpoint. On the > other hand, the fewer chunks you have the easier it is to manage the > server. > Tradeoffs and no hard rules. > > Art > > Art S. Kagel > Advanced DataTools (www.advancedatatools.com) IIUG Board of Directors > (art@iiug.org) > > See you at the 2010 IIUG Informix Conference April 25-28, 2010 Overland > Park > (Kansas City), KS www.iiug.org/conf > > Disclaimer: Please keep in mind that my own opinions are my own opinions > and > do not reflect on my employer, Advanced DataTools, the IIUG, nor any other > organization with which I am associated either explicitly, implicitly, or > by > inference. Neither do those opinions reflect those of other individuals > affiliated with any entity with which I am affiliated nor those of the > entities themselves. > > On Wed, Mar 31, 2010 at 3:04 PM, Wyza, Jonathon > <wyzaj@bethelcollege.edu>wrote: > > > This question was posted by someone on the list serve for the product > > I work with, but there hasn't been much of a response. I was hoping > > someone could answer the below as I'm interested in this as well. > > (note that this will relate to a SLES 11x64 IDS 11.50 box) > > > > I'm looking for opinions (facts acceptable too). > > > > We are in the hardware and disk layout phase of preparing for CX on > Linux. > > I > > look at our current system and see 5 chunks for our cars database > dbspace. > > They are each 2 GB for a total of 10GB. > > > > My question is: > > Should I set the new server up with one big chunk (~20GB) or break it > > up into more smaller chunks? > > > > Research: > > I have been searching for an answer to this question and do not find > > much guidance. I found that there used to be a 2GB size limit on a > > single chunk until Informix 9.4. There also used to be a limit on the > > number of chunks around 4000. I think the new limit on the number of > > chunks is 32766. I found one page that said with multiple chunks there > > are multiple threads to flush changes to disk so it takes less time to > > flush changes. There is an SAP tuning page that states that the ideal > > number of chunks for a dbspace is 1. Other than that don't have too > > much info. > > > > I would love to hear any opinions (or facts). > > > > Sean > > > > Jonathon Wyza > > CX & CBORD System Administrator > > CX Programmer/Analyst > > Administrative Computing > > Bethel College > > (574)-257-3381 > > AIM: Iamwyza > > jonathon.wyza@bethelcollege.edu<mailto:jonathon.wyza@bethelcollege.edu > > > > > ============================== > > SLES 10x32 SP2 & IDS 10.00.UC9 > > > > " I would love to change the world, but they won't give me the source > > code." > > -- Unknown > > > > > > > > > > > ******************************************************************************* > > Forum Note: Use "Reply" to post a response in the discussion forum. > > > > > > --00151748dd325cc9fc048322a139 > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --001517447bbc536a75048323b0c8