Gentoo Archives: gentoo-desktop

From: Paul Hartman <paul.hartman+gentoo@×××××.com>
To: gentoo-desktop@l.g.o
Subject: Re: [gentoo-desktop] System problems - some progress
Date: Thu, 24 Mar 2011 21:43:43
Message-Id: AANLkTim_TT2zEajqP0w+qtv9OEViwGebDV5-fKUesJxf@mail.gmail.com
In Reply to: Re: [gentoo-desktop] System problems - some progress by Lindsay Haisley
1 On Thu, Mar 24, 2011 at 3:38 PM, Lindsay Haisley <fmouse-gentoo@×××.com> wrote:
2 > On Thu, 2011-03-24 at 15:15 -0500, Paul Hartman wrote:
3 >> On Thu, Mar 24, 2011 at 1:16 PM, Lindsay Haisley <fmouse-gentoo@×××.com> wrote:
4 >> > The root of this problem is that on the old kernel, there are both
5 >> > a /dev/hda1 and a /dev/sda1.  The former is a partition on an old PATA
6 >> > drive, while the latter is a proper component of md0, but when
7 >> > everything becomes /dev/sdNx, there's an obvious conflict and the RAID
8 >> > subsystem is getting confused and is obviously not seeing it's sda1.
9 >>
10 >> Possible alternative is to disable raid autodetection and define the
11 >> arrays by UUID in /etc/mdadm.conf so hopefully the device names become
12 >> irrelevant at that point.
13 >
14 > This is a good idea.  I can turn off RAID autodetection in the kernel
15 > config and spec RAID1 instead, since the root fs isn't on a RAID array.
16 >
17 > I've found a number of references to putting UUIDs in ARRAY lines
18 > in /etc/mdadm.conf to define the UUID of an array, but none yet to using
19 > UUID specs in DEVICE lines, all of which I've found so far in the online
20 > literature use /dev/xxxx specs.  Before I take this step I'm going to
21 > find a more kernel-specific list and ask if this would be appropriate.
22 > I've tripped on RAID array errors before at the expense of days of work
23 > to reconstitute systems and their data.  I want to make sure this is
24 > kosher before I go there.
25
26 I was actually referring to the ARRAY lines and the array UUIDs. In
27 fact I don't even have a DEVICE line, man mdadm.conf says:
28 If no DEVICE line is present, then "DEVICE partitions containers" is assumed.
29
30 My mdadm.conf only contains 2 ARRAY lines, for my 2 raid arrays. I
31 also specify the metadata version, I assume you're using superblock
32 0.90 since you've been using autodetect and autodetect isn't supported
33 for newer versions.
34
35 So, mdadm scans all partitions (doesn't matter what they are named)
36 looking for superblocks containing the UUID of the arrays I specified.
37 Anything that doesn't match gets ignored for this purpose.
38
39 The mdadm manpage has this example command:
40
41 mdadm --examine --brief --scan --config=partitions
42 Create a list of devices by reading /proc/partitions, scan these for
43 RAID superblocks, and printout a brief listing of all that were
44 found.
45
46 Hopefully you can find your array UUIDs with that command (and if it
47 finds them, that's a good sign for it's ability to assemble the arrays
48 once the config file is made)
49
50 Good luck :)

Replies

Subject Author
Re: [gentoo-desktop] System problems - some progress Lindsay Haisley <fmouse-gentoo@×××.com>