[linux-lvm] LVM with multi-path disks?

[Luca Berra]

On Sun, Aug 05, 2001 at 12:32:57AM -0700, Mark Glines wrote:
> On Sun, Aug 05, 2001 at 09:12:01AM +0200, Luca Berra wrote:
> > there is an (*horrible*) piece of code in pv_read_all_pv.c
> > that deals with multiple entries for the same PV, so all duplicate
> > PV are skipped, so the md will be the obly one detected.
> > what probably happened to John is, that his PV was killed by
> > this routine (they were duplicate and not md devices)
> 
> I would only think this is a problem when md isn't being used.  In the
> above described situation, vgscan would see 2 devices which have md
> headers (and ignore them), and one LVM signature (and use it)?

Correct!

> If the code does what you say, and LVM was using the dual-path SCSI
> device directly, then it would detect one and ignore the other, and it
> would still work as if there was only one route to the drive.

this is also correct, i was just guessing there might be another dragon
in this code, but we would need an output of vgscan -d from John to check.

> However, in this case, md is in the middle, and its md's job to handle
> multi-path.  LVM should be ignoring md's lowlevel volumes anyway, and
> act solely on the virtual device md exports.  Am I missing something?
John is not using md yet, you are correct in all you say.

Regards,
L.
-- 
Luca Berra -- bluca at comedia.it
        Communication Media & Services S.r.l.
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