On Sat, May 30, 2009 at 5:53 PM, Neil Brown [off-list ref] wrote:

quoted

However, after a reboot, I'm back to 3 active and 0 spare drives. [snip]

This should "just work".  There might be some hints in
/var/log/messages if you'd like to post that.

Here is the output of `cat /var/log/messages | grep raid`:
http://pastebin.ca/1441575

It seems that raid5 only sees the sd[acd] as active drives, but
doesn't pick up the spare.

quoted

-- Is there any way to instantiate a superblock on /dev/sdb1 so that
it can be associated with this array's UUID?

You have already done that.  Use
  mdadm --examine /dev/sdb
to confirm.

This successfully identifies /dev/sdb1 as a spare: http://pastebin.ca/1441576
However running `mdadm --examine /dev/sda` for example does not:
http://pastebin.ca/1441578
And running `mdadm --detail /dev/md0` also says no spares:
http://pastebin.ca/1441579

(let me know if you'd rather I paste these inline, for archival
purposes or what have you)

quoted

-- I have the ARRAY line (in mdadm.conf) specified by UUID; could this
be causing the spare to be excluded, since it (presumably) does not
have a superblock?

No.  And it does have a superblock.

Gotcha, I stand corrected! I guess at this point I just need to figure
out how to get the spare to recognize on bootup, since it's already
got the same UUID and is listed in mdadm.conf:
http://pastebin.ca/1441588

Thanks again for your help,
Dave
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