This just happened to me. Create raid with: mdadm --create /dev/md2 --level=raid10 --raid-devices=3 --spare-devices=0 --layout=o2 /dev/sdb3 /dev/sdc3 /dev/sdd3 cat /proc/mdstat md2 : active raid10 sdd3[2] sdc3[1] sdb3[0] 5855424 blocks 64K chunks 2 offset-copies [3/3] [UUU] [==>..................] resync = 14.6% (859968/5855424) finish=1.3min speed=61426K/sec Some log messages: Dec 18 15:02:28 turnip kernel: md: md2: raid array is not clean -- starting background reconstruction Dec 18 15:02:28 turnip kernel: raid10: raid set md2 active with 3 out of 3 devices Dec 18 15:02:28 turnip kernel: md: resync of RAID array md2 Dec 18 15:02:28 turnip kernel: md: minimum _guaranteed_ speed: 1000 KB/sec/disk. Dec 18 15:02:28 turnip kernel: md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for resync. Dec 18 15:02:28 turnip kernel: md: using 128k window, over a total of 5855424 blocks. Dec 18 15:03:36 turnip kernel: md: md2: resync done. Dec 18 15:03:36 turnip kernel: md: checkpointing resync of md2. I tried to stop the array: mdadm --stop /dev/md2 and mdadm never came back. It's off in the kernel somewhere. :-( kill, of course, has no effect. The machine still runs fine, the rest of the raids (md0 and md1) work fine (same disks). The output (snipped, only mdadm) of 'echo t > /proc/sysrq-trigger' Dec 18 15:09:13 turnip kernel: mdadm S 0001e5359fa38fb0 0 3943 1 (NOTLB) Dec 18 15:09:13 turnip kernel: ffff810033e7ddc8 0000000000000086 0000000000000000 0000000000000092 Dec 18 15:09:13 turnip kernel: 0000000000000fc7 ffff810033e7dd78 ffffffff80617800 ffffffff80617800 Dec 18 15:09:13 turnip kernel: ffffffff8061d210 ffffffff80617800 ffffffff80617800 0000000000000000 Dec 18 15:09:13 turnip kernel: Call Trace: Dec 18 15:09:13 turnip kernel: [<ffffffff803fac96>] __mutex_lock_interruptible_slowpath+0x8b/0xca Dec 18 15:09:13 turnip kernel: [<ffffffff802acccb>] do_open+0x222/0x2a5 Dec 18 15:09:13 turnip kernel: [<ffffffff8038705d>] md_seq_show+0x127/0x6c1 Dec 18 15:09:13 turnip kernel: [<ffffffff80275597>] vma_merge+0x141/0x1ee Dec 18 15:09:13 turnip kernel: [<ffffffff802a2aa0>] seq_read+0x1bf/0x28b Dec 18 15:09:13 turnip kernel: [<ffffffff8028a42d>] vfs_read+0xcb/0x153 Dec 18 15:09:13 turnip kernel: [<ffffffff8028a7c1>] sys_read+0x45/0x6e Dec 18 15:09:13 turnip kernel: [<ffffffff80209c2e>] system_call+0x7e/0x83 What happened? Is there any debug info I can provide before I reboot? -- Jon - 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