Re: Informix DSA and RAID 5

Basically if you are going to use PDQ then you need to have fragmentation in place, which in turn needs many chunks. These chunks should ideally be placed on separate disk so to allow parallel reads to take place via the threads. Putting more than one of these chunks in the same raid LUN is going to have a negative impact on disk performance. We have conducted several tests that have proven this theory. However if you are not planning on fragmentation or PDQ stuff, then RAID can be used effectively. Noel.Yuhanna ------------------------------------------------------------------------ Manoj wrote: > > We are using raid 5 (DEC Storage works)with informix 7.22uc2 on a sun = > platform, (apparently it is supposed to be self learning in the number = > of hits on placements) and I can tell you I agree with the below: I = > would like to be able to control my own placement strategy. However = > there is software available that will give you some sort of say in the = > placement. > > Manoj (Two Way TV Ltd) > > -----Original Message----- > From: Billy Wheeler [SMTP:billy@west.co.za] > Sent: Thursday, May 08, 1997 2:08 PM > To: Jason A. Baines > Subject: Re: Informix DSA and RAID 5 > > On 7 May 97 at 19:41, Jason A. Baines wrote: > > > Can anybody shed any light on the advantages / disadvantages of using > > RAID 5 technology with our Informix DSA system. > >=20 > > ie somebody told me that the optimiser might not perform to its full > > benefits and table fragmentation would not be as useful. > > It's got people who love it and people who hate it. I hate it. I'd=20 > rather control my own placement strategy and use Informix mirroring=20 > for crucial DBspaces. > > FWIW. > > -- > Ciao, > Billy > > Nose to the ground and ear to the grindstone in: Kuwait City > > TAURUS > Apr. 20 - May 20 > You are practical and persistent. You have dogged > determination and work like hell. Most people > think you are stubborn and bullheaded. You are > nothing but a goddam communist.