2007/10/27, Rui Santos <rsantos@ruisantos.com>:
Hi Ciro,
Try to think of a RAID Array as a single partition. You put a filesystem "on top" of a partition or a RAID Array.
I know it's logically a partition/disk, but the important bit there is "logically", a real partition won't melt down or break into multiple unusable peaces.
If the power fails, the -partition- DOES "survive". The filesystem may have inconsistencies but it is probably recoverable. It is the same principle ( almost ) with a Soft-RAID array.
If you have frequent power loss, IMHO, you should activate RAID write-intent bitmapping. The command is mdadm /dev/mdX -Gb internal
That's what i'm talking about, i wonder if that has a performance penalty. This is the result of the last power outage: mainwks:~ # cat /proc/mdstat Personalities : [raid1] [raid0] [raid6] [raid5] [raid4] [linear] md0 : active raid1 sda1[0] sdb1[1] 104320 blocks [2/2] [UU] md1 : active raid1 sda3[0] sdb3[1] 241987008 blocks [2/2] [UU] [==>..................] resync = 11.0% (26760192/241987008) finish=315.0min speed=11384K/sec I assume that would look really nasty on a big raid5...
If you are afraid about a RAID's inconsistency by issuing "echo check >> /sys/block/mdX/md/sync_action" and check for failures wiht "cat /sys/block/mdX/md/mismatch_cnt". If there are failures, correct it with "echo repair >> /sys/block/mdX/md/sync_action"
You can also put it on a cron script...
Hope it helps, Rui
I will look further on the bitmapping topic. Thanks a lot Ciro -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org