On 2013-11-04, John R Pierce <pierce at hogranch.com> wrote: > On 11/4/2013 9:30 AM, Les Mikesell wrote: >>> Besides, if you have a problem with a truly humongous RAID, the rebuild >>> >will finish sometime around next summer.... >> Yes, I'd probably use a RAID10 style RAID so it runs at full speed >> even with a drive out of the array so you can put off the rebuild >> until a weekend. A rebuild will keep the heads too busy to do a lot >> of other work while it is running. > > > Using a common LSI Logic Megaraid card (9260-8i, I think, but don't > quote me), and 11 by 3TB raid6 with hotspares (using Seagate > Constellation.ES2 SAS2 drives), single drive failure rebuilds took 24 > hours, double drive failures took 36 hours, this with the system online > but mostly idle the whole time. yes, if you have steady user IO > activity going on the rebuild would take quite a bit longer, as it only > proceeds when the disks are idle. The MegaRAID controllers have a configurable rebuild rate. The default is 30%, but you can increase it up to 100% (which will probably kill your system IO). LSI 3ware controllers are also configurable in a similar way (their scale is only 1..5). --keith -- kkeller at wombat.san-francisco.ca.us