RE: Failed adadm RAID array after aborted Grown operation

[Bob Brand <brand@wmawater.com.au>]

Hi Wol,

My apologies for continually bothering you but I have a couple of questions:

1. How do I overcome the error message "mount: /dev/md125: can't read 
superblock."  Do it use fsck?

2. The removed disk is showing as "   -   0   0   30   removed". Is it safe 
to use "mdadm /dev/md2 -r detached" or "mdadm /dev/md2 -r failed" to 
overcome this?

Thank you!


-----Original Message-----
From: Bob Brand <brand@wmawater.com.au>
Sent: Monday, 9 May 2022 9:33 AM
To: Bob Brand <brand@wmawater.com.au>; Wol <antlists@youngman.org.uk>; 
linux-raid@vger.kernel.org
Cc: Phil Turmel <philip@turmel.org>
Subject: RE: Failed adadm RAID array after aborted Grown operation

I just tried it again with the --invalid_backup switch and it's now showing 
the State as "clean, degraded".and it's showing all the disks except for the 
suspect one that I removed.

I'm unable to mount it and see the contents. I get the error "mount:
/dev/md125: can't read superblock."

Is there more that I need to do?

Thanks


-----Original Message-----
From: Bob Brand <brand@wmawater.com.au>
Sent: Monday, 9 May 2022 9:02 AM
To: Bob Brand <brand@wmawater.com.au>; Wol <antlists@youngman.org.uk>; 
linux-raid@vger.kernel.org
Cc: Phil Turmel <philip@turmel.org>
Subject: RE: Failed adadm RAID array after aborted Grown operation

Hi Wol,

I've booted to the installation media and I've run the following command:

mdadm
/dev/md125 --assemble --update=revert-reshape --backup-file=/mnt/sysimage/grow_md125.bak
 --verbose --uuid= f9b65f55:5f257add:1140ccc0:46ca6c19
/dev/md125mdadm --assemble --update=revert-reshape --backup-file=/grow_md125.bak
  --verbose --uuid=f9b65f55:5f257add:1140ccc0:46ca6c19

But I'm still getting the error:

mdadm: /dev/md125 has an active reshape - checking if critical section needs 
to be restored
mdadm: No backup metadata on /mnt/sysimage/grow_md125.back
mdadm: Failed to find backup of critical section
mdadm: Failed to restore critical section for reshape, sorry.


Should I try the --invalid_backup switch or --force?

Thanks,
Bob


-----Original Message-----
From: Bob Brand <brand@wmawater.com.au>
Sent: Monday, 9 May 2022 8:19 AM
To: Wol <antlists@youngman.org.uk>; linux-raid@vger.kernel.org
Cc: Phil Turmel <philip@turmel.org>
Subject: RE: Failed adadm RAID array after aborted Grown operation

OK.  I've downloaded a Centos 7 - 2009 ISO from centos.org - that seems to
be the most recent they have.


-----Original Message-----
From: Wol <antlists@youngman.org.uk>
Sent: Monday, 9 May 2022 8:16 AM
To: Bob Brand <brand@wmawater.com.au>; linux-raid@vger.kernel.org
Cc: Phil Turmel <philip@turmel.org>
Subject: Re: Failed adadm RAID array after aborted Grown operation

How old is CentOS 7? With that kernel I guess it's quite old?

Try and get a CentOS 8.5 disk. At the end of the day, the version of linux
doesn't matter. What you need is an up-to-date rescue disk.
Distro/whatever is unimportant - what IS important is that you are using the
latest mdadm, and a kernel that matches.

The problem you have sounds like a long-standing but now-fixed bug. An
original CentOS disk might be okay (with matched kernel and mdadm), but
almost certainly has what I consider to be a "dodgy" version of mdadm.

If you can afford the downtime, after you've reverted the reshape, I'd try
starting it again with the rescue disk. It'll probably run fine. Let it
complete and then your old CentOS 7 will be fine with it.

Cheers,
Wol

On 08/05/2022 23:04, Bob Brand wrote:
> Thank Wol.
>
> Should I use a CentOS 7 disk or a CentOS disk?
>
> Thanks
>
> -----Original Message-----
> From: Wols Lists <antlists@youngman.org.uk>
> Sent: Monday, 9 May 2022 1:32 AM
> To: Bob Brand <brand@wmawater.com.au>; linux-raid@vger.kernel.org
> Cc: Phil Turmel <philip@turmel.org>
> Subject: Re: Failed adadm RAID array after aborted Grown operation
>
> On 08/05/2022 14:18, Bob Brand wrote:
>> If you’ve stuck with me and read all this way, thank you and I hope
>> you can help me.
>
> https://raid.wiki.kernel.org/index.php/Linux_Raid
>
> Especially
> https://raid.wiki.kernel.org/index.php/Linux_Raid#When_Things_Go_Wrogn
>
> What you need to do is revert the reshape. I know what may have
> happened, and what bothers me is your kernel version, 3.10.
>
> The first thing to try is to boot from up-to-date rescue media and see
> if an mdadm --revert works from there. If it does, your Centos should
> then bring everything back no problem.
>
> (You've currently got what I call a Frankensetup, a very old kernel, a
> pretty new mdadm, and a whole bunch of patches that does who knows what.
> You really need a matching kernel and mdadm, and your frankenkernel
> won't match anything ...)
>
> Let us know how that goes ...
>
> Cheers,
> Wol
>
>
>
> CAUTION!!! This E-mail originated from outside of WMA Water. Do not
> click links or open attachments unless you recognize the sender and
> know the content is safe.
>
>



CAUTION!!! This E-mail originated from outside of WMA Water. Do not click
links or open attachments unless you recognize the sender and know the
content is safe.