Performance impact with different page size
Hi, I am using informix 11.5 on Solaris and the database storage structure as one datadbs is with 16K page size second datadbs is with 4k page size and third datadbs is with 2k page size while log dbspace ,root dbspace and physical log dbspace is with 2k page size . My question is that when buffers of 16k and 4k will flush on logical and physical spaces spaces is there any chance of performance degradation? Please guide me I will be very thankful to you. Regards, Khurram Shahzad.
There is no way to know because the logical and physical log dbspaces MUST use the default pagesize, in your case that's 2K. Art On Apr 3, 2013 7:39 AM, "KHURRAM SHAHZAD" <kshahzad02@i2cinc.com> wrote: > Hi, > I am using informix 11.5 on Solaris and the database storage structure as > one > datadbs is with 16K page size second datadbs is with 4k page size and third > datadbs is with 2k page size while log dbspace ,root dbspace and physical > log > dbspace is with 2k page size . > > My question is that when buffers of 16k and 4k will flush on logical and > physical spaces spaces is there any chance of performance degradation? > > Please guide me I will be very thankful to you. > > Regards, > Khurram Shahzad. > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --bcaec554d2327ca92704d97384be
Hmmm.... buffers don't "flush on logical logs". They are written to physical log. For a 16KB buffer that you change, you'll get 4 pages of physical log. It will not necessarily mean you'll write 4 times instead of one. It depends on your physical buffer size. In any case, there is nothing you could do. The "system" dbspaces must be on the default page size for your platform. Currently we cannot change that. As for the logical logs, only the changes are written. Not whole pages, so the question does not exists for them. Regards. On Wed, Apr 3, 2013 at 12:38 PM, KHURRAM SHAHZAD <kshahzad02@i2cinc.com>wrote: > Hi, > I am using informix 11.5 on Solaris and the database storage structure as > one > datadbs is with 16K page size second datadbs is with 4k page size and third > datadbs is with 2k page size while log dbspace ,root dbspace and physical > log > dbspace is with 2k page size . > > My question is that when buffers of 16k and 4k will flush on logical and > physical spaces spaces is there any chance of performance degradation? > > Please guide me I will be very thankful to you. > > Regards, > Khurram Shahzad. > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > -- Fernando Nunes Portugal http://informix-technology.blogspot.com My email works... but I don't check it frequently... --bcaec501c04254155804d973b00d
We combine pages in the IO complex into 64K buffers. So during chunk writes as part of the checkpoint, since we do sorted writes, the writes= tend to be 'buddy-bunched'. This is one of the reasons that chunk IO i= s faster than LRU writes. Sent from my iPad On Apr 3, 2013, at 7:10 AM, "Fernando Nunes" <domusonline@gmail.com> wr= ote: > Hmmm.... buffers don't "flush on logical logs". They are written to > physical log. For a 16KB buffer that you change, you'll get 4 pages o= f > physical log. It will not necessarily mean you'll write 4 times inste= ad of > one. It depends on your physical buffer size. > In any case, there is nothing you could do. The "system" dbspaces mus= t be > on the default page size for your platform. Currently we cannot chang= e that. > As for the logical logs, only the changes are written. Not whole page= s, so > the question does not exists for them. > Regards. > > On Wed, Apr 3, 2013 at 12:38 PM, KHURRAM SHAHZAD <kshahzad02@i2cinc.com>wrote: > >> Hi, >> I am using informix 11.5 on Solaris and the database storage structu= re as >> one >> datadbs is with 16K page size second datadbs is with 4k page size an= d third >> datadbs is with 2k page size while log dbspace ,root dbspace and physical >> log >> dbspace is with 2k page size . >> >> My question is that when buffers of 16k and 4k will flush on logical= and >> physical spaces spaces is there any chance of performance degradatio= n? >> >> Please guide me I will be very thankful to you. >> >> Regards, >> Khurram Shahzad. > ***********************************************************************= ******** >> Forum Note: Use "Reply" to post a response in the discussion forum. > > -- > Fernando Nunes > Portugal > > http://informix-technology.blogspot.com > My email works... but I don't check it frequently... > > --bcaec501c04254155804d973b00d > > > ***********************************************************************= ******** > Forum Note: Use "Reply" to post a response in the discussion forum. >=