:: Re: [DNG] Some RAID1's inaccessible…
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Author: Hendrik Boom
To: dng
Subject: Re: [DNG] Some RAID1's inaccessible after upgrade to beowulf from ascii
On Tue, Nov 09, 2021 at 02:56:59PM -0500, Hendrik Boom via Dng wrote:
> I upgraded my server to beowulf.
> After rebooting, all home directories except root's are no longer
> accessible.
> They are all on an LVM on software RAID.
> The problem seems to be that two of my three RAID1 systems are not
> starting up properly. What can I do about it?

After following suggestions from the replies I got here, I determined
that one of my three physical disk drives was not being reognised by the
operating system.

Took the cover off the machine.

Looked in with a penlight and tured the machine off.

Wiggled and pushed on some SATA cables and power-supply cables.


All three drives came up properly. The RAIDs assembled properly.

All except /dev/md0. It's a defective RAID necause the disk drive
containing its second copy died a long time ago. I should move its data
off it onto one of the other RAIDs sometime.

Now there remains the question:

Why didn't /dev/md1 and /dev/md2 assemble properly as defective
RAID1s when their second copies were gone? Isn't that the whole point
of a RAID1?

/dev/md0 had no such problem.

-- hendrik

> hendrik@april:/$ cat /proc/mdstat
> Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5]
> [raid4] [raid10]
> md1 : inactive sda2[3](S)
>       2391296000 blocks super 1.2

> md2 : inactive sda3[0](S)
>       1048512 blocks

> md0 : active raid1 sdf4[1]
>       706337792 blocks [2/1] [_U]

> unused devices: <none>
> hendrik@april:/$
> hendrik@april:/$ cat /etc/mdadm/mdadm.conf
> DEVICE partitions
> ARRAY /dev/md0 level=raid1 num-devices=2
> UUID=4dc189ba:e7a12d38:e6262cdf:db1beda2
> ARRAY /dev/md1 metadata=1.2 name=april:1
> UUID=c328565c:16dce536:f16da6e2:db603645
> ARRAY /dev/md2 UUID=5d63f486:183fd2ea:c2a3a88f:cb2b61de
> hendrik@april:/$
> The standard recommendation seems to be to replace lines
> in /etc/mdadm/mdadm.conf by lines prouced by mdadm --examine --scan:
> april:~# mdadm --examine --scan
> ARRAY /dev/md/1 metadata=1.2 UUID=c328565c:16dce536:f16da6e2:db603645
> name=april:1
> ARRAY /dev/md2 UUID=5d63f486:183fd2ea:c2a3a88f:cb2b61de
> ARRAY /dev/md0 UUID=4dc189ba:e7a12d38:e6262cdf:db1beda2
> april:~#
> But this replacement involves changing a line that dies work (md0),
> not changing one that did not (md2),
> and changing another one that did not work (md1).
> Since --examine's suggested changes seem uncorrelated
> with the active/inactive record, I have little faith in
> this alleged fix without first gaining more understanding.
> -- hendrik

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