On Thu, Jan 01, 2015 at 8:54 PM, Robert L Mathews wrote: >> I recently made a RAID1 array from a couple of extra usb drives: >> $ mdadm --create --metadata 1.2 --verbose /dev/md/backup --level=mirror -n2 /dev/sd[cd]2 > > These are sdc2 and sdd2. Okay. > >> Personalities : [raid1] md126 : active (auto-read-only) raid1 >> sdc2[0] >> 943587136 blocks super 1.2 [2/1] [U_] >> >> md127 : active (auto-read-only) raid1 sdd2[1] >> 943587136 blocks super 1.2 [2/1] [_U] > > Still sdc2 and sdd2, although now in two arrays. > >> AFAIK both drives are healthy, but since that happened, it refuses >> to assemble them both in the array: >> $ mdadm --assemble --force /dev/md/backup /dev/sd[db]2 >> mdadm: ignoring /dev/sdb2 as it reports /dev/sdd2 as failed > > Now you're working on sdb2 and sdd2. Is that intentional? Did sdc2 > become sdb2 after a restart or something? Yes. They're just two of three external usb disks. The lettering depends on the order in which I power up the computer and the drives. I believe I read that mdadm works even when the device names change. It did seem to be working before this issue arose. >> Is there any way to put the array back together without having to >> resync? > > You should collect more data about what array each partition thinks > it's a member of, etc., before you try anything else. People can > probably help more if you report the output of these to the list: > > mdadm --detail /dev/md* I had to assemble the array, but as above, it only includes one device. While doing this I discovered one of the usb cables is flaky, which explains why the device (sdc below) wasn't always coming on line. $ mdadm --assemble --force /dev/md/backup /dev/sd[cd]2 mdadm: ignoring /dev/sdc2 as it reports /dev/sdd2 as failed mdadm: /dev/md/backup has been started with 1 drive (out of 2). $ mdadm --detail /dev/md/* /dev/md/backup: Version : 1.2 Creation Time : Wed Dec 17 22:39:10 2014 Raid Level : raid1 Array Size : 943587136 (899.87 GiB 966.23 GB) Used Dev Size : 943587136 (899.87 GiB 966.23 GB) Raid Devices : 2 Total Devices : 1 Persistence : Superblock is persistent Update Time : Tue Dec 30 08:06:51 2014 State : clean, degraded Active Devices : 1 Working Devices : 1 Failed Devices : 0 Spare Devices : 0 Name : deb76:backup (local to host deb76) UUID : ee0bd35a:727132cc:b4230313:69d3cbd7 Events : 382 Number Major Minor RaidDevice State 0 0 0 0 removed 1 8 50 1 active sync /dev/sdd2 > mdadm --examine /dev/sd* I won't bore you with sda and sdb, there's nothing raid-related on them. $ mdadm --examine /dev/sd[cd]{,2} /dev/sdc: MBR Magic : aa55 Partition[0] : 16777216 sectors at 16384 (type 83) Partition[1] : 1887436800 sectors at 16793600 (type da) /dev/sdd: MBR Magic : aa55 Partition[0] : 16777216 sectors at 16384 (type 83) Partition[1] : 1887436800 sectors at 16793600 (type da) /dev/sdc2: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : ee0bd35a:727132cc:b4230313:69d3cbd7 Name : deb76:backup (local to host deb76) Creation Time : Wed Dec 17 22:39:10 2014 Raid Level : raid1 Raid Devices : 2 Avail Dev Size : 1887174656 (899.88 GiB 966.23 GB) Array Size : 943587136 (899.87 GiB 966.23 GB) Used Dev Size : 1887174272 (899.87 GiB 966.23 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : 0347f019:c7911229:bde3bb2e:847aeebc Update Time : Sun Dec 28 21:20:46 2014 Checksum : 7cd44677 - correct Events : 38 Device Role : Active device 0 Array State : A. ('A' == active, '.' == missing) /dev/sdd2: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : ee0bd35a:727132cc:b4230313:69d3cbd7 Name : deb76:backup (local to host deb76) Creation Time : Wed Dec 17 22:39:10 2014 Raid Level : raid1 Raid Devices : 2 Avail Dev Size : 1887174656 (899.88 GiB 966.23 GB) Array Size : 943587136 (899.87 GiB 966.23 GB) Used Dev Size : 1887174272 (899.87 GiB 966.23 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : d2c29953:34be093c:00279411:674cd53e Update Time : Tue Dec 30 08:06:51 2014 Checksum : 2e39ee1c - correct Events : 382 Device Role : Active device 1 Array State : .A ('A' == active, '.' == missing) -- 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