RE: Stripesize on Informix Raw devices
Does the recommendation of a 16K stripe size also hold for AIX platforms and others which have a 4K page size? Or should the stripe size by 32K (or 8 pages)? Your recommendations would be appreciated. Thanks, Rick Bernstein > -----Original Message----- > From: Art S. Kagel [mailto:kagel@bloomberg.net] > Sent: Monday, October 11, 1999 10:34 > To: informix-list@iiug.org > Subject: Re: Stripesize on Informix Raw devices > > > The best stripe size for Informix is 16K. Informix either > does BUFFER > writes of 2K or BIGWRITES of 16K so the 16K normally works out best. > Remember that Informix is not normally write intensive, due to it's > excellent buffer cache, so unless you are really stressing > the system it > may be very difficult to detect any improvement from striped -vs- > singleton drives. You will see the biggest improvement from watching > your checkpoint durations during load. Data load tests will > rarely be > affected by disk layout unless the loadset it MUCH larger > than the buffer > cache and is being inserted by MANY independent processes or threads. > > Art S. Kagel > > Marc Hopkins wrote: > > > > Does anyone have any experience with striping data on > Informix raw devices. > > We are running HPUX 10.20 on K420's. Informix reads and > writes in 2K pages. > > I have tried the stripesize of 4, which is the minimum HP > allows, and > > performance has not been any better than non-striped data. > I have the data > > striped across four disks. Anyone else using a diff > stripesize? I am not > > sure if I need to take into account the Informix Read-Ahead > configuration. > > Any suggestions welcome. Please send responses to email. > > > > Thanks, > > Marc > > marc.hopkins@aei.com >
Yes since all Informix I/O is in pages the 8page BIGREAD and BIGWRITE holds so on AIX the ideal stripe size would probably be 32K. Art S. Kagel "Bernstein, Rick" wrote: > > Does the recommendation of a 16K stripe size also hold for > AIX platforms and others which have a 4K page size? > Or should the stripe size by 32K (or 8 pages)? > > Your recommendations would be appreciated. > Thanks, > Rick Bernstein > > > -----Original Message----- > > From: Art S. Kagel [mailto:kagel@bloomberg.net] > > Sent: Monday, October 11, 1999 10:34 > > To: informix-list@iiug.org > > Subject: Re: Stripesize on Informix Raw devices > > > > > > The best stripe size for Informix is 16K. Informix either > > does BUFFER > > writes of 2K or BIGWRITES of 16K so the 16K normally works out best. > > Remember that Informix is not normally write intensive, due to it's > > excellent buffer cache, so unless you are really stressing > > the system it > > may be very difficult to detect any improvement from striped -vs- > > singleton drives. You will see the biggest improvement from watching > > your checkpoint durations during load. Data load tests will > > rarely be > > affected by disk layout unless the loadset it MUCH larger > > than the buffer > > cache and is being inserted by MANY independent processes or threads. > > > > Art S. Kagel > > > > Marc Hopkins wrote: > > > > > > Does anyone have any experience with striping data on > > Informix raw devices. > > > We are running HPUX 10.20 on K420's. Informix reads and > > writes in 2K pages. > > > I have tried the stripesize of 4, which is the minimum HP > > allows, and > > > performance has not been any better than non-striped data. > > I have the data > > > striped across four disks. Anyone else using a diff > > stripesize? I am not > > > sure if I need to take into account the Informix Read-Ahead > > configuration. > > > Any suggestions welcome. Please send responses to email. > > > > > > Thanks, > > > Marc > > > marc.hopkins@aei.com > >