Here are the results of the tests I ran to check the raid reconstruct speed of a node in an 880c with 72GB drives. The filer was not being used, so the only load was the reconstruct. This is just the base time to reconstruct. One can find a multiplier that can be used to determine the reconstruct speed with the avg load on their filers....although I don't know how easy that would be to find.
RAID set size Elapsed (time to reconstruct) 2 29:43.70 (29 min, 43.70 sec) 3 39:59.72 4 51:58.87 5 1:04:17.90 6 1:16:40.76 7 1:29:39.19 8 1:43:01.75 9 1:56:02.55 10 2:09:19.00 11 2:22:39.12
As you can see the time to reconstruct appears to go up by about 11-14 minutes when adding an additional disk. More info on tests: cluster 880 all disks were on the same shelf: DS14 all disks were zero'ed before the reconstruct raid.reconstruct.perf_impact medium raid.resync.perf_impact medium
procedure repeated for each raid size: -priv set diag -setflag raid_enable_prezeroing 1 after done all disks zero'ed -setflag raid_enable_prezeroing 0 -vol create vol1 -r 14 11 after volume is created -disk fail (parity disk in vol1) times taken -vol offline vol1 -vol destroy vol1 -disk unfail (disk failed)