Hi. I'm running Linux 2.6.26 with mdadm v2.6.1. Over the past 24 hours I've several times set up a 400GB raid1 md array in a recovery/resync operation which has subsequently hung the system. In five such operations three have hung: o I added a third disk drive to a working raid1 md device; after an hour or more of active synchronisation the system hung. o after pulling out the third (hot pluggable) disk I rebooted the system, which started resyncing the md device upon assembly. This operation also hung after about an hour. o rebooting again and this time reducing all activity on the system to an absolute minimum the resync succeeded. o I tried again to mirror the md device to my third hot-pluggable disk by inserting the drive and attaching it to the raid1 md device; after an hour or so the recovery hung again. o rebooting again with the third drive unplugged it looks like the resync is going to run to completion this time. All three disks are Western Digital SATA 2 drives. SMART says there's no problems with the drives. A resync/recover operation typically proceeds at an average speed of about 35MB/sec, as reported by /proc/mdstat. But then - for the times that it hung - /proc/mdstat reports slower and slower speeds and longer and longer finish times (30,000 minutes plus!). In /sys/block/md1/md the value of sync_completed would stay static and sync_speed would drop lower and lower (< 1000KB/sec). I tried: echo 40960 > sync_speed_min in an attempt to try and coax things to go faster but the system remained hung. The system was hung in that: o load average increased to about 13; top reported 50% spent in 'wait time'; o Any operation that accessed the disk/md device would 'hang'. Other trivial operations - shell builtin commands, X11 widget updates - still worked. 'shutdown -r now' wouldn't work; I had to cold-boot the system each time. o No error messages logged to the console or syslog. This 'hang' *seems* to be related to system activity; the system has never been *heavily* loaded the three times a resync/recover operation failed but I had a couple of download programs and the like - keeping the network interface mildly busy - running in every failed/hung case. Ideally the resync/recover operation should proceed independent of the system activity, I would have thought? I'd hoped to be able to perform daily/weekly transparent backups by plugging in the third drive, adding it to the raid1 md device and then detaching the disk after the recover operation had completed. Can anyone help? I have no idea if there are other things I can do or tune to get around this problem, or if it's an actual bug. I had a look in the kernel archives but couldn't see anything that seemed relevant to this problem with the latest stable kernel. Thanks, Brad -- 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
