progress, but... - re. fixing LVM/md snafu

progress, but... - re. fixing LVM/md snafu

[Miles Fidelman]

Hello again Folks,

So.. I'm getting closer to fixing this messed up machine.

Where things stand:

I have root defined as an LVM2 LV, that should use /dev/md2 as it's PV.
/dev/md2 in turn is a RAID1 array built from /dev/sda3 /dev/sdb3 and 
/dev/sdc3

Instead, LVM is reporting: "Found duplicate PV 
2ppSS2q0kO3t0tuf8t6S19qY3ypWBOxF: using /dev/sdb3 not /dev/sda3"
and the /dev/md2 is reporting itself as inactive (cat /proc/mdstat) and 
active,degraded (mdadm --detail)

---
I'm guessing that, during boot:

- the raid array failed to start
- LVM found both copies of the PV, and picked one (/dev/sdb3)
- everything then came up and my server is humming away

but: the md array can't rebuild because the most current device in it is 
already in use

so...  I'm looking for the right sequence of events, with the minimum 
downtime to:

1. stop changes to /dev/sdb3 (actually, to / - which complicates things)
2. rebuild the RAID1 array, making sure to use /dev/sdb3 as the starting 
point for current data
3. restart in such a way that LVM finds /dev/md2 as the right PVM 
instead of one of its components

Each of these is just tricky enough that I'm sure there are lots of 
gotchas to watch out for.

So.. any suggestions?

Thanks very much,

Miles Fidelman




_______________________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: progress, but... - re. fixing LVM/md snafu

[Goswin von Brederlow]

Miles Fidelman <mfidelman@traversetechnologies.com> writes:

> Hello again Folks,
>
> So.. I'm getting closer to fixing this messed up machine.
>
> Where things stand:
>
> I have root defined as an LVM2 LV, that should use /dev/md2 as it's PV.
> /dev/md2 in turn is a RAID1 array built from /dev/sda3 /dev/sdb3 and
> /dev/sdc3
>
> Instead, LVM is reporting: "Found duplicate PV
> 2ppSS2q0kO3t0tuf8t6S19qY3ypWBOxF: using /dev/sdb3 not /dev/sda3"
> and the /dev/md2 is reporting itself as inactive (cat /proc/mdstat)
> and active,degraded (mdadm --detail)

So you didn't tell lvm.conf to ignore raid component devices or the
detection fails. Worst case exclude sd?3 manualy.

After that a reboot should fix it.

MfG
        Goswin