According to your output your Raid1 has failed. It looks like one of the drives is disconnected or has failed. Look at Total Device number = 1, it should be 2 since your doing Raid 1 with 2 devices. ALso - look at State = Clean,degraded, it should say clean I would make sure all your data is backed up before you start doing anything else. Good luck! On 04/01/2012 01:10 PM, Mike Miller wrote: > I want to be sure that my RAID1 is working properly. What's the best way > to do that? I tried mdadm --detail (see below) and I guess mdadm thinks > it is working, but one part surprises me: "Array Size" is different for > the two disks. Is that normal? The disks are two identical 2TB drives. > > Mike > > > $ sudo mdadm --detail /dev/md[01] > [sudo] password for [user]: /dev/md0: > Version : 00.90 > Creation Time : Tue Oct 4 11:45:48 2011 > Raid Level : raid1 > Array Size : 1945312384 (1855.19 GiB 1992.00 GB) > Used Dev Size : 1945312384 (1855.19 GiB 1992.00 GB) > Raid Devices : 2 > Total Devices : 1 > Preferred Minor : 0 > Persistence : Superblock is persistent > > Update Time : Sun Apr 1 12:54:52 2012 > State : clean, degraded > Active Devices : 1 > Working Devices : 1 > Failed Devices : 0 > Spare Devices : 0 > > UUID : d64b75e8:e8767139:e368bf24:bd0fce41 > Events : 0.2357380 > > Number Major Minor RaidDevice State > 0 8 1 0 active sync /dev/sda1 > 1 0 0 1 removed > /dev/md1: > Version : 00.90 > Creation Time : Tue Oct 4 11:46:13 2011 > Raid Level : raid1 > Array Size : 8200960 (7.82 GiB 8.40 GB) > Used Dev Size : 8200960 (7.82 GiB 8.40 GB) > Raid Devices : 2 > Total Devices : 1 > Preferred Minor : 1 > Persistence : Superblock is persistent > > Update Time : Sun Apr 1 00:57:01 2012 > State : clean, degraded > Active Devices : 1 > Working Devices : 1 > Failed Devices : 0 > Spare Devices : 0 > > UUID : 90b1095c:d6dd36a1:e368bf24:bd0fce41 > Events : 0.241 > > Number Major Minor RaidDevice State > 0 8 2 0 active sync /dev/sda2 > 1 0 0 1 removed > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > tclug-list at mn-linux.org > http://mailman.mn-linux.org/mailman/listinfo/tclug-list