Linux RAID subsystem development
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From: Joe Landman <joe.landman@gmail.com>
To: Bryan Hepworth <bryan.hepworth@newcastle.ac.uk>,
	"linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org>
Subject: Re: force raid reassembly
Date: Tue, 8 Aug 2017 15:44:04 -0700	[thread overview]
Message-ID: <e6fff4a2-ebce-0c85-e2a5-d9cef0a27043@gmail.com> (raw)
In-Reply-To: <WM!bafd27028d31e7e922c12b615def50baa8369ba598ac220b2884f1706eddac34cd0580e2d54cc3da9be1bbadf104dab1!@mailhub-mx1.ncl.ac.uk>



On 8/8/17 3:27 PM, Bryan Hepworth wrote:
> Hi all
>
> I'd be grateful of another pair of eyes just to check and verify what I'm thinking. I've had an array fail and I've checked the components with the mdadm --examine command. Five out of the six event counts are correct and I'm hoping I can get it to assemble with the force option: -
>
> "mdadm --assemble --force /dev/mdX <list of devices>"
>
> mdadm --assemble --force /dev/md0 /dev/sdd1 /dev/sdg1 /dev/sdf1 /dev/sde1 /dev/sdb1 /dev/sdc1

I don't think you need to explicitly list the devices (/dev/sd(..)) in 
the force

You could do something like this:

mdadm --examine --scan | grep md0 > /tmp/md0.conf
mdadm -As -c /tmp/md0.conf

if this doesn't work, then the force *may* be an option, but be very 
careful with this.
>
> Output from --examine is as follows: -
>
>
> [root@inscribe4 dev]# mdadm --examine /dev/sde1
> /dev/sde1:
>            Magic : a92b4efc
>          Version : 1.2
>      Feature Map : 0x1
>       Array UUID : ace00fb5:8771d55a:cf36728b:ddc3ce89
>             Name : intermediate0
>    Creation Time : Tue Oct 15 21:03:50 2013
>       Raid Level : raid5
>     Raid Devices : 6
>
>   Avail Dev Size : 3906761858 (1862.89 GiB 2000.26 GB)
>       Array Size : 9766901760 (9314.44 GiB 10001.31 GB)
>    Used Dev Size : 3906760704 (1862.89 GiB 2000.26 GB)
>      Data Offset : 262144 sectors
>     Super Offset : 8 sectors
>     Unused Space : before=262064 sectors, after=1154 sectors
>            State : clean
>      Device UUID : 8d0b6c8e:0c526265:6ec0a71b:52a636ba
>
> Internal Bitmap : 8 sectors from superblock
>      Update Time : Tue Aug  8 14:16:53 2017
>         Checksum : 44b7b461 - correct
>           Events : 119894
>
>           Layout : left-symmetric
>       Chunk Size : 512K
>
>     Device Role : spare
>     Array State : AAA.A. ('A' == active, '.' == missing, 'R' == replacing)
>
> [root@inscribe4 dev]# mdadm --examine /dev/sdg1
> /dev/sdg1:
>            Magic : a92b4efc
>          Version : 1.2
>      Feature Map : 0x1
>       Array UUID : ace00fb5:8771d55a:cf36728b:ddc3ce89
>             Name : intermediate0
>    Creation Time : Tue Oct 15 21:03:50 2013
>       Raid Level : raid5
>     Raid Devices : 6
>
>   Avail Dev Size : 3906761858 (1862.89 GiB 2000.26 GB)
>       Array Size : 9766901760 (9314.44 GiB 10001.31 GB)
>    Used Dev Size : 3906760704 (1862.89 GiB 2000.26 GB)
>      Data Offset : 262144 sectors
>     Super Offset : 8 sectors
>     Unused Space : before=262064 sectors, after=1154 sectors
>            State : clean
>      Device UUID : e238e74b:d40efc43:d34d876d:ca0700b0
>
> Internal Bitmap : 8 sectors from superblock
>      Update Time : Tue Aug  8 14:16:53 2017
>         Checksum : 28758d54 - correct
>           Events : 119894
>
>           Layout : left-symmetric
>       Chunk Size : 512K
>
>     Device Role : Active device 1
>     Array State : AAA.A. ('A' == active, '.' == missing, 'R' == replacing)
>
> [root@inscribe4 dev]# mdadm --examine /dev/sdd1
> /dev/sdd1:
>            Magic : a92b4efc
>          Version : 1.2
>      Feature Map : 0x1
>       Array UUID : ace00fb5:8771d55a:cf36728b:ddc3ce89
>             Name : intermediate0
>    Creation Time : Tue Oct 15 21:03:50 2013
>       Raid Level : raid5
>     Raid Devices : 6
>
>   Avail Dev Size : 3906761858 (1862.89 GiB 2000.26 GB)
>       Array Size : 9766901760 (9314.44 GiB 10001.31 GB)
>    Used Dev Size : 3906760704 (1862.89 GiB 2000.26 GB)
>      Data Offset : 262144 sectors
>     Super Offset : 8 sectors
>     Unused Space : before=262064 sectors, after=1154 sectors
>            State : clean
>      Device UUID : 1732f121:f6f0df09:fafd2411:7c78ce00
>
> Internal Bitmap : 8 sectors from superblock
>      Update Time : Tue Aug  8 14:16:53 2017
>         Checksum : b8cf8981 - correct
>           Events : 119894
>
>           Layout : left-symmetric
>       Chunk Size : 512K
>
>     Device Role : Active device 0
>     Array State : AAA.A. ('A' == active, '.' == missing, 'R' == replacing)
>
> [root@inscribe4 dev]# mdadm --examine /dev/sdf1
> /dev/sdf1:
>            Magic : a92b4efc
>          Version : 1.2
>      Feature Map : 0x1
>       Array UUID : ace00fb5:8771d55a:cf36728b:ddc3ce89
>             Name : intermediate0
>    Creation Time : Tue Oct 15 21:03:50 2013
>       Raid Level : raid5
>     Raid Devices : 6
>
>   Avail Dev Size : 3906761858 (1862.89 GiB 2000.26 GB)
>       Array Size : 9766901760 (9314.44 GiB 10001.31 GB)
>    Used Dev Size : 3906760704 (1862.89 GiB 2000.26 GB)
>      Data Offset : 262144 sectors
>     Super Offset : 8 sectors
>     Unused Space : before=262064 sectors, after=1154 sectors
>            State : clean
>      Device UUID : 3d414ad2:4310c1f9:98f50214:3e9b1e33
>
> Internal Bitmap : 8 sectors from superblock
>      Update Time : Tue Aug  8 14:16:53 2017
>         Checksum : 8e37d25d - correct
>           Events : 119894
>
>           Layout : left-symmetric
>       Chunk Size : 512K
>
>     Device Role : Active device 2
>     Array State : AAA.A. ('A' == active, '.' == missing, 'R' == replacing)
>
> [root@inscribe4 dev]# mdadm --examine /dev/sdb1
> /dev/sdb1:
>            Magic : a92b4efc
>          Version : 1.2
>      Feature Map : 0x1
>       Array UUID : ace00fb5:8771d55a:cf36728b:ddc3ce89
>             Name : intermediate0
>    Creation Time : Tue Oct 15 21:03:50 2013
>       Raid Level : raid5
>     Raid Devices : 6
>
>   Avail Dev Size : 3906761858 (1862.89 GiB 2000.26 GB)
>       Array Size : 9766901760 (9314.44 GiB 10001.31 GB)
>    Used Dev Size : 3906760704 (1862.89 GiB 2000.26 GB)
>      Data Offset : 262144 sectors
>     Super Offset : 8 sectors
>     Unused Space : before=262064 sectors, after=1154 sectors
>            State : clean
>      Device UUID : a84263cd:75ce20b9:a3a72a1c:b18b2457
>
> Internal Bitmap : 8 sectors from superblock
>      Update Time : Mon Jul 31 22:50:37 2017
>         Checksum : 74d320d6 - correct
>           Events : 119879
>
>           Layout : left-symmetric
>       Chunk Size : 512K
>
>     Device Role : Active device 5
>     Array State : AAA.AA ('A' == active, '.' == missing, 'R' == replacing)
>
> [root@inscribe4 dev]# mdadm --examine /dev/sdc1
> /dev/sdc1:
>            Magic : a92b4efc
>          Version : 1.2
>      Feature Map : 0x1
>       Array UUID : ace00fb5:8771d55a:cf36728b:ddc3ce89
>             Name : intermediate0
>    Creation Time : Tue Oct 15 21:03:50 2013
>       Raid Level : raid5
>     Raid Devices : 6
>
>   Avail Dev Size : 3906761858 (1862.89 GiB 2000.26 GB)
>       Array Size : 9766901760 (9314.44 GiB 10001.31 GB)
>    Used Dev Size : 3906760704 (1862.89 GiB 2000.26 GB)
>      Data Offset : 262144 sectors
>     Super Offset : 8 sectors
>     Unused Space : before=262064 sectors, after=1154 sectors
>            State : clean
>      Device UUID : be5ec20e:249645e5:22aeca25:a60c7599
>
> Internal Bitmap : 8 sectors from superblock
>      Update Time : Tue Aug  8 14:16:53 2017
>         Checksum : 2e529fae - correct
>           Events : 119894
>
>           Layout : left-symmetric
>       Chunk Size : 512K
>
>     Device Role : Active device 4
>     Array State : AAA.A. ('A' == active, '.' == missing, 'R' == replacing)
>
> Thanks
>
> Bryan
> --
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-- 
Joe Landman
e: joe.landman@gmail.com
t: @hpcjoe
c: +1 734 612 4615
w: https://scalability.org
g: https://github.com/joelandman
l: https://www.linkedin.com/in/joelandman


  reply	other threads:[~2017-08-08 22:44 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <DB4PR07MB409B56E9B9173E33079902ED58A0@DB4PR07MB409.eurprd07.prod.outlook.com>
2017-08-08 22:27 ` force raid reassembly Bryan Hepworth
2017-08-08 22:44   ` Joe Landman [this message]
     [not found]     ` <DB4PR07MB40970AB64E677A452895432D58B0@DB4PR07MB409.eurprd07.prod.outlook.com>
     [not found]       ` <WM!c7e5d36941a99d370e99c9ecff040c34199c6ab48c7c1548590a2e9075a62b0e4a8a44d8c43afabb53f77be4c9108e21!@mailhub-mx3.ncl.ac.uk>
2017-08-09  7:40         ` Bryan Hepworth
2017-08-09 10:34   ` Joe Landman
2017-08-12 17:44     ` Anthony Youngman
     [not found]       ` <DBXPR07MB415CB58355ECBF4DB0D6632D59B0@DBXPR07MB415.eurprd07.prod.outlook.com>
     [not found]         ` <WM!13c5dc8d433950e8d178eb39ac57b28caef2d362792181894459f3aa56870cedd0dcd8b5aa75be7d1b060d3021a4afe9!@mailhub-mx3.ncl.ac.uk>
2017-08-25  8:03           ` Bryan Hepworth

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