Which RAID to use?
Hello! We are about to embark on the creation of a fail over database server using 2 Sun 4500's and an EMC Clarion disk array with 720 GB disk space. We have been struggling with the all important question of which RAID level to use. I have heard bad stories of RAID 5 failing because 2 disk drives crash with in hours of each other. Also, the performance of writes with RAID 5 is a concern. On the up side you are able to take advantage of more disk space. RAID 0+1 seems to be the most tested and proven. Any suggestions? Thanks very much in advance! Ronald Twaddell DBA Nexigent Inc ronald.twaddell@nexigent.com ----------------------------------------------------- Confidentiality Notice: This e-mail transmission may contain confidential or legally privileged information that is intended only for the individual or entity named in the e-mail address. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, or reliance upon the contents of this e-mail is strictly prohibited. If you have received this e-mail transmission in error, please reply to the sender, so that Nexigent can arrange for proper delivery, and then please delete the message from your inbox. Thank you.
FWIW, we used RAID 5, until we ran across Art Kagel's insightful rantings on the subject. After some internal discussions we moved to RAID 10. We also have a second solution. We have a part of our production database housed on a SEEK SYSTEMS raid array. It uses an adaptive technology to dynamically decide what RAID set up may work best. The system monitors data access and then reconfigures itself on the fly. We use a system with a single hot-swappable spare, but the truly paranoid may run it with several hot-spares. I have no financial interest in SEEK. We are satisfied customers. Cheers-- Charles Twaddell, Ronald <Ronald.Twaddell@nexigent.com> wrote in article <92vacv$agh$1@news.xmission.com>... > > Hello! > > We are about to embark on the creation of a fail over database server using > 2 Sun 4500's and an EMC Clarion disk array with 720 GB disk space. We have > been struggling with the all important question of which RAID level to use. > > > I have heard bad stories of RAID 5 failing because 2 disk drives crash with > in hours of each other. Also, the performance of writes with RAID 5 is a > concern. On the up side you are able to take advantage of more disk space. > > RAID 0+1 seems to be the most tested and proven. > > Any suggestions? > > Thanks very much in advance! > > Ronald Twaddell > DBA > Nexigent Inc > ronald.twaddell@nexigent.com > > > > ----------------------------------------------------- > Confidentiality Notice: This e-mail transmission > may contain confidential or legally privileged > information that is intended only for the individual > or entity named in the e-mail address. If you are not > the intended recipient, you are hereby notified that > any disclosure, copying, distribution, or reliance > upon the contents of this e-mail is strictly prohibited. > > If you have received this e-mail transmission in error, > please reply to the sender, so that Nexigent can arrange > for proper delivery, and then please delete the message > from your inbox. Thank you. >
If you can afford RADI 0+1, use it. The scenario you describe with RAID 5 is theoretically realistic. A RAID 5 array can tolerate the loss of one disk, but in the (unlikely) event that you lose another disk at the same time, then your RAID 5 filesystem will break. Twaddell, Ronald <Ronald.Twaddell@nexigent.com> wrote in message news:92vacv$agh$1@news.xmission.com... > > Hello! > > We are about to embark on the creation of a fail over database server using > 2 Sun 4500's and an EMC Clarion disk array with 720 GB disk space. We have > been struggling with the all important question of which RAID level to use. > > > I have heard bad stories of RAID 5 failing because 2 disk drives crash with > in hours of each other. Also, the performance of writes with RAID 5 is a > concern. On the up side you are able to take advantage of more disk space. > > RAID 0+1 seems to be the most tested and proven. > > Any suggestions? > > Thanks very much in advance! > > Ronald Twaddell > DBA > Nexigent Inc > ronald.twaddell@nexigent.com > > > > ----------------------------------------------------- > Confidentiality Notice: This e-mail transmission > may contain confidential or legally privileged > information that is intended only for the individual > or entity named in the e-mail address. If you are not > the intended recipient, you are hereby notified that > any disclosure, copying, distribution, or reliance > upon the contents of this e-mail is strictly prohibited. > > If you have received this e-mail transmission in error, > please reply to the sender, so that Nexigent can arrange > for proper delivery, and then please delete the message > from your inbox. Thank you.