On Monday 25 August 2014 13:35:11 Kerin Millar wrote:
> On 25/08/2014 12:17, Peter Humphrey wrote:
>
> <snip>
>
> > Well, it was simple. I just said "rc-update del mdraid boot" and all is
> > now
> > well. I'd better revisit the docs to see if they still give the same
> > advice.
>
> Very interesting indeed.
You wrote this e-mail after the other two, so I'll stick to this route,
leaving the other idea for later if needed.
> I now wonder if this is a race condition between the init script running
> `mdadm -As` and the fact that the mdadm package installs udev rules that
> allow for automatic incremental assembly?
Isn't it just that, with the kernel auto-assembly of the root partition, and
udev rules having assembled the rest, all the work's been done by the time the
mdraid init script is called? I had wondered about the time that udev startup
takes; assembling the raids would account for it.
> Refer to /lib/udev/rules.d/64-md-raid.rules and you'll see that it calls
> `mdadm --incremental` for newly added devices.
# ls -l /lib/udev/rules.d | grep raid
-rw-r--r-- 1 root root 2.1K Aug 23 10:34 63-md-raid-arrays.rules
-rw-r--r-- 1 root root 1.4K Aug 23 10:34 64-md-raid-assembly.rules
> With that in mind, here's something else for you to try. Doing this will
> render these udev rules null and void:
>
> # touch /etc/udev/rules.d/64-md-raid.rules
I did that, but I think I need instead to
# touch /etc/udev/rules.d/63-md-raid-arrays.rules
# touch /etc/udev/rules.d/64-md-raid-assembly.rules
I'll try it now...
> Thereafter, the mdraid script will be the only agent trying to assemble
> the 1.x metadata arrays so make sure that it is re-enabled.
Right. Here's the position:
1. I've left /etc/init.d/mdraid out of all run levels. I have nothing but
comments in mdadm.conf, but then it's not likely to be read anyway if
the
init script isn't running.
2. I have empty /etc/udev rules files as above.
3. I have kernel auto-assembly of raid enabled.
4. I don't use an init ram disk.
5. The root partition is on /dev/md5 (0.99 metadata)
6. All other partitions except /boot are under /dev/vg7 which is built on
top of /dev/md7 (1.x metadata).
7. The system boots normally.
> I'm not actually sure that there is any point in calling mdadm -As where
> the udev rules are present. I would expect it to be one approach or the
> other, but not both at the same time.
That makes sense to me too. Do I even need sys-fs/mdadm installed? Maybe I'll
try removing it. I have a little rescue system in the same box, so it'd be
easy to put it back if necessary.
> Incidentally, the udev rules were a source of controversy in the
> following bug. Not everyone appreciates that they are installed by default.
>
> https://bugs.gentoo.org/show_bug.cgi?id=401707
I'll have a look at that - thanks.
--
Regards
Peter
