1 |
Thanks, Paul. |
2 |
|
3 |
On Thu, 2011-03-24 at 16:42 -0500, Paul Hartman wrote: |
4 |
> I was actually referring to the ARRAY lines and the array UUIDs. In |
5 |
> fact I don't even have a DEVICE line, man mdadm.conf says: |
6 |
> If no DEVICE line is present, then "DEVICE partitions containers" is |
7 |
> assumed. |
8 |
> |
9 |
> My mdadm.conf only contains 2 ARRAY lines, for my 2 raid arrays. I |
10 |
> also specify the metadata version, I assume you're using superblock |
11 |
> 0.90 since you've been using autodetect and autodetect isn't supported |
12 |
> for newer versions. |
13 |
|
14 |
Newer versions? Kernel 2.6.36 has a config option for RAID autodetect. |
15 |
What are you referring to here, mdadm? |
16 |
|
17 |
mdadm is at 2.6.8 on this box. If I upgrade to v3.1.4 will I lose the |
18 |
ability to autodetect the arrays, on which the system depends even on |
19 |
the 2.6.23 kernel on which I'm currently depending? |
20 |
|
21 |
> So, mdadm scans all partitions (doesn't matter what they are named) |
22 |
> looking for superblocks containing the UUID of the arrays I specified. |
23 |
> Anything that doesn't match gets ignored for this purpose. |
24 |
|
25 |
> The mdadm manpage has this example command: |
26 |
|
27 |
> mdadm --examine --brief --scan --config=partitions |
28 |
|
29 |
So I get: |
30 |
|
31 |
# mdadm --examine --brief --scan --config=partitions |
32 |
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=d3176595:06cb3677:46406ca7:d12d146f |
33 |
ARRAY /dev/md1 level=raid1 num-devices=2 UUID=9463a434:24dbfcb6:a25ffb08:d8ab7c18 |
34 |
|
35 |
... which is what I would expect. |
36 |
|
37 |
Does this mean that the UUID of the _array_ has been pushed onto the |
38 |
component drives? If so, why does the RAID assembly fail so miserably |
39 |
with kernel 2.6.36? I'm lost here. It looks to me, from the boot log, |
40 |
as if the problem is that there are _two_ partitions named /dev/sda1 and |
41 |
the RAID subsystem can't see the one that's a component of |
42 |
md0. /etc/mdadm.conf contains: |
43 |
|
44 |
DEVICE /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 |
45 |
ARRAY /dev/md0 devices=/dev/sda1,/dev/sdb1 |
46 |
ARRAY /dev/md1 devices=/dev/sdc1,/dev/sdd1 |
47 |
|
48 |
> Create a list of devices by reading /proc/partitions, scan these for |
49 |
> RAID superblocks, and printout a brief listing of all that were |
50 |
> found. |
51 |
|
52 |
This gives me the UUIDs of the arrays, but my question here is whether I |
53 |
can spec the component devices using UUIDs, and I'm not finding any |
54 |
clear guidance on that. The mdadm man page talks about the former, but |
55 |
doesn't mention the latter. In other words, can I put into mdadm.conf a |
56 |
line such as the following: |
57 |
|
58 |
ARRAY /dev/md0 devices=UUID=d3176595-06cb-3677-4640-6ca7d12d146f,UUID=d3176595-06cb-3677-4640-6ca7d12d146f |
59 |
|
60 |
> Hopefully you can find your array UUIDs with that command (and if it |
61 |
> finds them, that's a good sign for it's ability to assemble the arrays |
62 |
> once the config file is made) |
63 |
|
64 |
Finding the ARRAY UUIDs isn't the problem, it's assigning the array |
65 |
components using _their_ respective UUIDs. If I can do this, the |
66 |
problem may be solved. |
67 |
|
68 |
I don't know that this will work, I don't know that it won't. I have |
69 |
everything on the arrays, and the LVMs built on them, backed up. I |
70 |
probably should just try it and back out of it if it doesn't, since I |
71 |
don't see any potential for data loss if it fails, in which case the |
72 |
RAID arrays simply won't be built and I'll be dumped into the workable |
73 |
but not very useful non-RAID configuration. |
74 |
|
75 |
-- |
76 |
Lindsay Haisley | "The difference between a duck is because |
77 |
FMP Computer Services | one leg is both the same" |
78 |
512-259-1190 | - Anonymous |
79 |
http://www.fmp.com | |