Re: [gentoo-user] General weirdness - a tale of woe.

[Peter Humphrey]

On Thursday 28 May 2015 19:51:24 Rich Freeman wrote:
> On Thu, May 28, 2015 at 1:03 PM, Peter Humphrey <peter@××××××××××××.uk>
wrote:
> > I've found blkid, which tells me the UUIDs of my various devices, thus:
> >
> > # blkid /dev/md7
> > /dev/md7: UUID="ycGMf9-hEP2-tjT4-AtkJ-n8RI-pZ44-RqvlEY"
> > TYPE="LVM2_member"
>
> Just keep in mind that the UUID that goes into mdadm.conf might not be
> the same UUID returned by blkid.  I'm honestly not certain either way.
> You can get the mdadm ID from mdadm --detail --scan.

Good grief! When is a UUID not a UUID? Or, how can one device have more than 
one UUID?


> > Two odd things:
> > 1.      /dev/md7 is the physical volume in which logical volumes are
> > defined, so I'm surprised to see TYPE="LVM2_member".
>
> I'm pretty sure this is fine.  It recognizes it as an LVM pv, so that
> makes it an LVM2 member.

If you say so. It still smells a bit to me.

> > 2.      There is no entry corresponding to /dev/md7 under
> > /dev/disk/by-uuid, though /dev/md1 and /dev/md5 do have entries there
> > [1].
>
> udev may be configured to not create uuid symlinks for LVM pvs (since
> you wouldn't directly mount them anyway).  The others contain
> filesystems and do get symlinks.
>
> > What should I be doing about this?
>
> I'd probably just edit your mdadm.conf to be more liberal with
> scanning, and add the arrays output by mdadm --detail --scan to your
> config file.  That alone may make your problems go away, and it should
> be pretty harmless.

OK, so this is what I have at present. I haven't booted with it yet to test it 
- I'll do that in the morning:

DEVICE /dev/sd[abcde][123456789]
ARRAY /dev/md1 UUID=ea156c7f:183ca28e:c44c77eb:7ee19756
ARRAY /dev/md5 UUID=e7640378:966a5b3a:c44c77eb:7ee19756
ARRAY /dev/md7 UUID=c2d056c4:9118021f:ad73c633:b38fa97c

> Nothing about what you've written here concerns me.

Well, let us be thankful for small mercies :-)

-- 
Rgds
Peter