Thread (7 messages) 7 messages, 2 authors, 2013-10-10

Re: Broken array, trying to assemble enough to copy data off

From: Digimer <hidden>
Date: 2013-10-10 16:54:44

On 10/10/13 12:36, Phil Turmel wrote:
On 10/10/2013 12:20 PM, Digimer wrote:
quoted
quoted
Phil
Ya, I have no plan at all to use these drives or the server they came
from anymore. In fact, they've already been replaced. :)
That's good.
quoted
I tried the --assemble --force (and --assemble --force --run) without
success. It fails saying that sde2 thinks sdb2 has failed, leaving two
dead members. If I try to start with just sd[bcd], it says that it has
two drives and one spare, so still refuses to start.
Ok.
quoted
Any other options/ideas? I'm not in any rush, so I am happy to test things.
Well, you have rock-solid knowledge of the device order and array
parameters.  So a --create operation is the next step.  Given that sdd2
is marked as spare, and therefore of unknown value, I'd leave it out.

mdadm --stop /dev/md1
mdadm --create --level=5 -n 4 --chunk=512 /dev/md1 \
	/dev/sd{c,e,b}2 missing

(--assume-clean isn't needed when creating a degraded raid5)

The brace syntax is needed, not brackets, as the order matters.

After creation, use mdadm -E to verify the Data Offset is 2048.  If not,
get a new version of mdadm that lets you specify it.

Only after that should you use "fsck -n" to verify your filesystem and
mount it.

HTH,

Phil
What if I don't have rock-solid knowledge? Is there a way to connect the
four drives and query them to determine which is which? I was using the
new system (minus the new drives) plus a spare new 500GB drive with the
fresh centos install to do the testing yesterday. I am pretty sure I can
redo the cabling to match, but I always prefer safe over sorry. :)

Thanks very much for your help so far!

digimer

-- 
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without
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