Re: How many drives are bad?

[Neil Brown <neilb@suse.de>]

On Tuesday February 19, normelton@gmail.com wrote:
> So I had my first "failure" today, when I got a report that one drive
> (/dev/sdam) failed. I've attached the output of "mdadm --detail". It
> appears that two drives are listed as "removed", but the array is
> still functioning. What does this mean? How many drives actually
> failed?

The array is configured for 8 devices, but on 6 are active.  So you
have lost data.
Of the two missing devices, one is still in the array and is marked as
fault.  One is simply not present at all.
Hence "Failed Devices: 1".  i.e. there is one failed device in the
array.

It looks like you have been running a degraded array for a while
(maybe not a long while) and the device has then failed.

"mdadm --monitor"

will send you mail if you have a degraded array.

NeilBrown

> 
> This is all a test system, so I can dink around as much as necessary.
> Thanks for any advice!
> 
> Norman Elton
> 
> ====== OUTPUT OF MDADM =====
> 
>         Version : 00.90.03
>   Creation Time : Fri Jan 18 13:17:33 2008
>      Raid Level : raid5
>      Array Size : 6837319552 (6520.58 GiB 7001.42 GB)
>     Device Size : 976759936 (931.51 GiB 1000.20 GB)
>    Raid Devices : 8
>   Total Devices : 7
> Preferred Minor : 4
>     Persistence : Superblock is persistent
> 
>     Update Time : Mon Feb 18 11:49:13 2008
>           State : clean, degraded
>  Active Devices : 6
> Working Devices : 6
>  Failed Devices : 1
>   Spare Devices : 0
> 
>          Layout : left-symmetric
>      Chunk Size : 64K
> 
>            UUID : b16bdcaf:a20192fb:39c74cb8:e5e60b20
>          Events : 0.110
> 
>     Number   Major   Minor   RaidDevice State
>        0      66        1        0      active sync   /dev/sdag1
>        1      66       17        1      active sync   /dev/sdah1
>        2      66       33        2      active sync   /dev/sdai1
>        3      66       49        3      active sync   /dev/sdaj1
>        4      66       65        4      active sync   /dev/sdak1
>        5       0        0        5      removed
>        6       0        0        6      removed
>        7      66      113        7      active sync   /dev/sdan1
> 
>        8      66       97        -      faulty spare   /dev/sdam1
> -
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