Scott Burns said: > William Hooper wrote: > >> >>Of course if both disks of a mirror set die you lose everything, too. >> >> >> > Yes. > > The guy was recommending RAID10 ( a bunch of RAID1 pairs then add them > all together as RAID0 ). > > After reading it I worked out a number comparing a RAID5 with 5 disks > against RAID10 with 4 stripped sets of 3 disks (12 in total ). If you > lose 2/5 RAID5 disks you are all lost. Apples and oranges. If you are going to compare multiple sets, why not compare 4 RAID5 sets w/ 3 disks each (12 in total). > If you lose 5/12 RAID10s you > still have over a 95% chance of no data lost. I believe recovery time > on RAID10 puts RAID5 to shame too. His entire rant can be found at > http://groups.google.com.au/groups?q=quarterly+raid+5+rant+group:comp.databases.informix&hl=en&lr=&ie=UTF-8&group=comp.databases.informix&selm=pan.2003.07.31.16.49.22.318281.15473%40bloomberg.net&rnum=5 > He answers your question there: "Well with RAID10 there is no danger unless the one mirror that is recovering also fails and that's 80% or more less likely than that any other drive in a RAID5 array will fail!" Of course, he falls into the same trap you did, comparing a single RAID5 set with multiple RAID10 sets. -- William Hooper
