RE: force raid reassembly

-----Original Message-----
From: Joe Landman [mailto:joe.landman@gmail.com]
Sent: 08 August 2017 23:44
To: Bryan Hepworth; linux-raid@vger.kernel.org
Subject: Re: force raid reassembly



On 8/8/17 3:27 PM, Bryan Hepworth wrote:

quoted

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: -

quoted

"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.

quoted

Hi Joe

Thanks for the reply, unfortunately that came back as follows: -

[root@inscribe4 ~]# mdadm --examine --scan
ARRAY /dev/md/intermediate1  metadata=1.2 UUID=64a34aa3:3703e1b0:37d3173a:bec0c874 name=intermediate1
ARRAY /dev/md/intermediate0  metadata=1.2 UUID=ace00fb5:8771d55a:cf36728b:ddc3ce89 name=intermediate0
   spares=1
ARRAY /dev/md/128  metadata=1.2 UUID=d59b4fac:ade4fdbf:13ebe850:5e70ba42 name=igmimager.ncl.ac.uk:128

[root@inscribe4 md]# mdadm --examine --scan | grep intermediate0 > /tmp/intermediate0.conf
[root@inscribe4 md]# cat /tmp/intermediate0.conf
ARRAY /dev/md/intermediate0  metadata=1.2 UUID=ace00fb5:8771d55a:cf36728b:ddc3ce89 name=intermediate0
[root@inscribe4 md]# mdadm --assemble --scan -c /tmp/intermediate0.conf
mdadm: /dev/md/intermediate0 assembled from 4 drives and 1 spare - not enough to start the array.
[root@inscribe4 md]#

Looks like I'll have to use the force option unless you can think of a better way

Thanks

Bryan