On 11/16/2010 10:47 AM, John R Pierce wrote: > > raid sets really shouldn't be much bigger than about 8 drives, > anyways. rebuild times for a 12 drive raid6 would be astronomical. > You are ok up to here. Rebuild time for replacement of a failed drive scales by drive size, not raid set size, regardless of whether it is RAID1, 5, 6 or 10. It remains roughly the amount of time it takes to completely write one drive at full speed (at least unless you run out of bus bandwidth - but that takes a lot of drives). However, system availability/performance is much better for RAID10 than for the others during a rebuild because of the isolation of the rebuild work to only the involved spindles. -- Benjamin Franz