OK :) David Niccolo Rigacci wrote: > 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). > > > -- - 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
