From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wols Lists <antlists@youngman.org.uk>
Subject: Re: Need help with degraded raid 5
Date: Thu, 5 Mar 2020 17:22:20 +0000
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To: Jinpu Wang <jinpuwang@gmail.com>, William Morgan <therealbrewer@gmail.com>
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On 05/03/20 14:53, Jinpu Wang wrote:
> "mdadm /dev/md0 -a /dev/sdl1"  should work for you to add the disk
> back to array, maybe you can check first with "mdadm -E /dev/sdl1" to
> make sure.

Or better, --re-add or whatever the option is. If it can find the
relevant data in the superblock, like bitmap or journal or whatever, it
will just bring the disk up-to-date. If it can't, it functions just like
add, so you've lost nothing but might gain a lot.

Cheers,
Wol