On Sun, 1 Apr 2012, Marc Skinner wrote:

> 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.


Is it possible that it was just set up wrong in the first place?  Do you 
know why it says "Failed Devices: 0"?  I don't understand the output, but 
does this imply that the drive appears as if it had been removed:

     Number   Major   Minor   RaidDevice State
        0       8        2        0      active sync   /dev/sda2
        1       0        0        1      removed

I was assuming it was right and I didn't know how to test it after I first 
set it up.  I'm more aware now about that issue.

Thanks.

Mike


> 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