Thanks to the several guys in this list, I have solved my problem and elaborated this, can be a new FAQ entry? Q: Sometimes when a RAID volume is resyncing, the system seems to locks-up: every disk activity is blocked until resync is done. A: This is not strictly related to Linux RAID, this is a problem related to the Linux kernel and the disk subsytem: in no circumstances a process should get all the disk resources preventing others to access them. You can control the max speed at which RAID reconstruction is done by setting it, say at 5 Mb/s: echo 5000 > /proc/sys/dev/raid/speed_limit_max This is just a workaround, you have to determine the max speed that does not lock your system by trial and error and you cannot predict what will be the disk load in the future when the RAID will be resyncing for some reason. Starting from version 2.6, Linux kernel has several choices about the I/O scheduler to be used. The default is the anticipatory scheduler, which seems to be sub-optimal on resync high load. If your kernel has the CFQ scheduler compiled in, use it during resync. >From the command line you can see which schedulers are supported and change it on the fly (remember to do it for each RAID disk): # cat /sys/block/hda/queue/scheduler noop [anticipatory] deadline cfq # echo cfq > /sys/block/hda/queue/scheduler Otherwise you can recompile your kernel and set CFQ as the default I/O scheduler (CONFIG_DEFAULT_CFQ=y in Block layer, IO Schedulers, Default I/O scheduler). -- Niccolo Rigacci Firenze - Italy Iraq, missione di pace: 38475 morti - www.iraqbodycount.net - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
