Re: RAID1 with multiple partitions
On Fri, Dec 17, 2010 at 1:17 AM, Bob Proulx <bob@proulx.com> wrote:
> Tom H wrote:
>> Both "mdadm --detail /dev/mdX" and "mdadm --examine /dev/sdXY" will
>> output "(local to host <hostname>)" on the uuid line for metadata
>> v0.90 and on the name line for metadata v1.x.
>
> I never see that[1] and therefore conclude that if HOMEHOST is never
> set in the configuration file that it will not set it in the
> superblock. (Because I don't set it and I don't see it while you do
> set it and you do see it.)
>
> [1] Here is an example of output from one of my systems.
>
> $ sudo mdadm --detail /dev/md3
> Version : 0.90
> UUID : 92ad3585:f8512ceb:e680833b:09bbf4f8
>
> $ sudo mdadm --examine /dev/sda7
> Version : 0.90.00
> UUID : 92ad3585:f8512ceb:e680833b:09bbf4f8
I've just checked a lenny and a squeeze box.
The lenny box is using metadata v0.9 and there is a "(local to...)" on
the UUID line. It was created without specifying either "--homehost="
or "--name=" when running "mdadm --create" on a running system (using
the standard "sfdisk -d ... | sfdisk ..." and "mdadm --create ...",
etc).
The squeeze box is using metadata v1.2 and there is a name line with
"(local to host...)" both for an array created by the installer and an
array created without specifying either "--homehost=" or "--name="
when running "mdadm --create ...".
So I have no idea why your output doesn't show "(local to host...)"!
>> When you refer to "/dev/mdX_Y", do you mean partitionable arrays
>> (/dev/md/dX", "/dev/md/dXpY")?
>
> I was referring to this part of the documentation:
>
> When arrays are assembled using auto-assembly, arrays
> which do not record the correct homehost name in their
> metadata will be assembled using a "foreign" name. A
> "foreign" name always ends with a digit string preceded
> by an underscore to differentiate it from any possible
> local name. e.g. /dev/md/1_1 or /dev/md/home_0.
(I found this by running "man mdadm" and "man mdadm.conf" on both the
boxes above and, of course, found it with the fourth try...) :)
Thanks, I'd never seen this text before (I guess that I haven't run
"man mdadm.conf" on squeeze before!). I added a "foreign" array to a
sid box a few months ago and the foreign arrays were renamed
"/dev/md126" and "/dev/md127" like lenny. There may also have been
"/dev/md/0_0" and "/dev/md/1_1" devices or symlinks created. If I do
this again on squeeze or sid, I'll have to check the contents of
"/dev/md/".
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