Re: Informix on Raid 5

On Mon, 3 Feb 1997 21:06:15 +0000, David Williams <djw@smooth1.demon.co.uk> wrote: >In article <01bc0fdb$eeed12e0$1d6a93c0@dashforcash.chrims.com>, * ><smitty@chrims.com> writes >>Hello >> I have a question regarding increased performance from the informix engine >>when used on a RAID 5 system in a sco unix environment. My programmers tell >>me that the system would be faster useing a multidrive config. than with >>Raid. Please respond with any experiences or knowledge regarding this >>subject. >> > > I believe RAID 5 is the version which has very poor write performance. > This is because all of the parity info is stored on one disk. This > means that EVERY write involves one write to the parity disk. > > You would get better peformance with RAID 1 (i.e. mirroring) where > not all writes involve writing to the same disk drive which becomes > a bottleneck. > > >-- >David Williams This is only true if you are NOT using a Fast Wide SCSI2 or similar controller. With a good caching controller RAID 5 canm arguably be way faster than RAID 1 due to parallel write capability. (Table fragmentation without the hassle) Michael