Re: Informix Online 5 running on RAID5

Keith Gerritsen (keithg@enerco.co.nz) wrote: : We are preparing to implement 3 Informix Databases on a DEC Alpha with a : RAID5 Array configuration. : Does anyone have any comments regarding performance of RAID5 with : Informix Online ver 5 verses a RAID 1 or 0 configuration? especially with : OSF/1 ver 3.0 If I understand my RAID numbers correctly (which I might not) and RAID 1 is simply disk striping with no data integrity features like mirroring then I've had a little experience in this area with a Pyramid MIS-4S and Online v4.12. In some crude tests I did by simply using timex to run some of our batch jobs. I tested with the rootdbs and a userdbs both on the same physical partition/drive and then with rootdbs and the userdbs on the same logical partition after it had been striped across several drives. In general I found that the jobs would run marginally slower or a lot slower depending upon how the clustering was configured for the striped partition. When I say "marginally slower" I mean that if the job took about 5 minutes to run on the same physical drive/partition then it would usually take about 2 minutes longer on the stripped partition. I believe the reason that the striping didn't help is because of the randomness of the reads and writes imposed by my batch jobs. If there had been more sequential reads/writes then they might have run faster. Given that striping is part of a virtual disk facility within the Pyramid, I opted to not use it since it didn't seem to be gaining me any performance and since it was only RAID 1(?) it would have been more risky having the data spread out like this. -- +--------------------+----------------------------+--------------------------+ | Michael Faurot | mfaurot@phzzzt.atww.org | I don't like | | ------- ------ | | lima beans!! | +--------------------+----------------------------+--------------------------+