Re: INFORMIX-OnLine DSA and RAID: which level is the best?

We also had an Informix Raid 5 system (about 180GB) and had nothing but trouble. After changing to Raid 0+1, we have had nearly continuous uptime and very few downtimes. It is my opinion that Raid 5 and Informix do not mix. --Stuart scott@tiga.worldaccess.nl (S. Hanson) wrote: >Melvin Perez Cedano wrote: >> >> Hello Informixers: >> >> I would like to get some opinions about your experiences using >> INFORMIX-OnLine DSA version 7.x and RAID disks. I would like to get your >> opinions concerning to performance and mirroring. >> >> This is for an OLTP application on IBM RS/6000 family. >> >> >> Thanks in advance, >> >> >> Melvin Perez Cedano >> Technical Vicepresident >> CAM Informatica, S. A. >> >This topic has been covered recently but here are my opinions. >It really depends which level of RAID you are using. If you are using >RAID 1 (mirroring) then it is no problem. > >If you are using RAID 5 (striping) then, in my experience, it is better >not to use RAID 5 disks for Informix since you do not really know which >spindle you are working with, so it is difficult to tune Informix. > >If you plan to use the RAID with other applications than Informix >simultaneously, then forget it. Then heads of the disks will not stay in >the Informix partition but will jump all over the place drastically >reducing your performance. > >Another issue is that Informix can only handle chunks <= 2GB, so you >would need to partition the RAID. Use 2GB disks for optimum performance. >We threw out our 16GB RAID 5 box for 8x2GB mirrored disks and we now run >about 10 times faster. >Scott >Scott Hanson Junior Consultant >scott@worldaccess.nl NexTime B.V. office: (31) 10 207 5400 >www.worldaccess.nl/~scott The Netherlands fax: (31) 10 456 9122