Apparently a RAIDZ2 with 9 disks is computationally expensive: my system got as low as 34% CPU Idle when doing one disk rebuild (and one other disk offline). The CPU isn’t exactly fast (Athlon 64 X2 4600+) but I didn’t expect the usage to be this high. I’ll see how it goes after rebuild finished. Good thing I cancelled my plan of using an Atom for my other file server.
last pid: 62412; load averages: 1.34, 1.28, 1.25 up 0+02:39:21 01:32:32 54 processes: 1 running, 52 sleeping, 1 zombie CPU: 0.0% user, 0.0% nice, 63.2% system, 1.9% interrupt, 34.9% idle Mem: 46M Active, 32M Inact, 4654M Wired, 104K Cache, 85M Buf, 1160M Free Swap: 400M Total, 400M Free