On 11/16/2010 09:25 AM, John R Pierce wrote: > > These days of cheap drives, I use raid10 almost exclusively. and if its > at all mission critical, I like to have 1-2 hotspares. if I was > deploying a new server, and its workload was at all database-centric, > I'd want to use use 2.5" SAS rather than 3.5" SATA > > With RAID10, the rebuild time is how long it takes to copy the one > drive. if you have 6 drives in a raid10 and one fails, leaving 5, and > another fails, there's only a 1 in 5 chance of that other failure being > the mirror of the dead drive. If you have a hot spare, that > rebuild starts immediately, reducing the window for that dreaded double > failure to a minimum. > Oh, I agree - and when price is no object, or if write performance is the bottleneck, or if you need huge numbers of drives, I love RAID10. You can take it to crazy levels of redundancy + performance by going to RAID0 layered over multiple three-way RAID1 arrays. Why have multiple hotspares when you can go for N>2-RAID1 + 0 instead and get a hefty performance boost on reads for almost free at even higher reliability? -- Benjamin Franz