On 6/12/2014 12:30 PM, Dan Ritter wrote:
On Thu, Jun 12, 2014 at 12:10:17PM -0400, Bill Horne wrote:
The machine came with a default Ubuntu 13.04 LTS install, which
includes an LVM on /dev/sda, and a blank /dev/sdb. The plan is to
create a degraded RAID1 array on the "spare" drive, and then copy
the "live" drive data into it and subsequently join the two drives
together in a RAID1 array, with LVM on top of RAID1.
However, we know what they say about the best laid plans ...
I've managed to create some sort of array, named "md127", but I
haven't been able to figure out how. I did an "mdadm --create" with
a name of "md1", but I've wound up with "md127". It appears to be
working, albeit in degraded mode, but I want to go slowly and figure
out what happened before I wind up with a non-standard install which
might cause problems later.
That's an easy one. mdadm doesn't guarantee naming by device, so
you need to either label your partitions (e2label) or use their
UUIDs (ls -al /dev/disk/by-uuid to figure it out) and then put
them in /etc/fstab as:
LABEL=whatever / ext3 defaults 0 0
or
UUID=big-long-string / ext3 defaults 0 0
as appropriate. UUID and label are both guaranteed to survive
anything that leaves the disk readable. UUID is
cross-filesystem.
UUID can also be used in mdadm as device names, and that is
recommended.
Thanks for your suggestion. I'm going to "test for transfer": just being
cautious, etc.
When I do "ls -al /dev/disk/by-uuid", I get
telecomdigest5@telecom-new:~$ sudo ls -al /dev/disk/by-uuid
[sudo] password for moder8:
total 0
drwxr-xr-x 2 root root 140 Jun 12 11:07 .
drwxr-xr-x 5 root root 100 Jun 12 00:09 ..
lrwxrwxrwx 1 root root 10 Jun 12 00:10
3eebd0ba-ddf4-46ff-8610-505d56de8360 -> ../../dm-0
lrwxrwxrwx 1 root root 10 Jun 12 00:10
50a377af-31bb-46df-b901-3dc84ddcece4 -> ../../sda1
lrwxrwxrwx 1 root root 10 Jun 12 00:10
69d83c29-0475-470d-9465-650f7d4ddd9f -> ../../dm-1
lrwxrwxrwx 1 root root 10 Jun 12 00:10
902c123b-6a15-4508-8989-0bd4673570b2 -> ../../sdb4
lrwxrwxrwx 1 root root 11 Jun 12 11:07
d8bdbfe5-dfa2-437c-97f2-1d87f265bd3f -> ../../md127
However, when I enter the command "sudo mdadm --detail --scan", I get
ARRAY /dev/md/telecom-new:md1 metadata=1.2 name=telecom-new:md1
UUID=c4e39dd8:541c124b:bd60a9b1:339d6e3e
... and since the UUID's aren't matching up, I'm in need of some
reassurance that I'm not about to brick the machine by using this RAID1
"ARRAY".
it: of course, that's not the final state I'm aiming for, but for
now I know that it is working with the "md127" name. I don't know
how I wound up with the "md127" name instead of "md1", but if
there's no danger sign in that name, I'm happy to go to the next
step and make "md127" part of the LVM and proceed to add /dev/sda to
the RAID1 array.
You're fine, but you probably want to specify it by UUID for /dev/sda,
not "/dev/sda".
Good point, but I'm stuck at the point where the UUID's in "md127"
don't match "md1".
BTW, I'd be fine with nuking the raid1 array(s) I have now and starting
over if that's the easier way. How would I do that?
Bill
--
Bill Horne
William Warren Consulting
339-364-8487
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