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

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