[DRBD-user] Why isn't DRBD recognized as valid LVM PV?

Ralph.Grothe at itdz-berlin.de Ralph.Grothe at itdz-berlin.de
Thu Mar 13 12:36:07 CET 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hi Florian,

> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com
> [mailto:drbd-user-bounces at lists.linbit.com]On Behalf Of Florian
Haas
> Sent: Wednesday, March 12, 2008 7:08 PM
> To: drbd-user at lists.linbit.com
> Subject: Re: [DRBD-user] Why isn't DRBD recognized as valid LVM
PV?
> 
> 
> You know, reading http://www.drbd.org/users-guide/ch-lvm.html 
> (the whole 
> chapter, not just the first section) would have saved you a lot
of 
> experimentation effort. ;-)

Yes, you are absolutely right.

at http://www.drbd.org/users-guide/s-lvm-drbd-as-pv.html

this is the info that I was obviously missing:

<quote>
You may of course use a different filter  configuration to match
your particular system configuration. What is important to
remember, however, is that you need to

    *

      Accept (include) the DRBD devices you wish to use as PVs;
    *

      Reject (exclude) the corresponding lower-level devices, so
as to avoid LVM finding duplicate PV signatures.
</quote>

I apologize having unnecessarily bothered people here.

I simply wasn't aware that these things were outlined here
somewhere expressis verbis.

To my apology you might concede that I wasn't the person who
originally set up the formerly HB1 DRBD7 cluster
but only the one charged with updating the OS on the cluster
nodes
(with no written down documentation or recipe from my ancestor),
and that this has been my first exposure to DRBD.
All I had used so far was the documentation of the manpages 
(I am really a fan of manpages and would wish that developers put
more care and detail in them;
I think the *BSD or HP-UX manpages are a lucid epitome; haven't
yet reconciled with info pages)

So I thought, well by simply looking and poking around on the
existing node
that I would finally find out myself what was required.
But as often, this has been hubris and one falls in one of these
tiny pits like unfit lvm.conf etc.

Now, slowly exploring your fine documentation, I must
congratulate you on that
as it seems to detail everything what is required by the average
admin.

Regards

Ralph




> 
> On Wednesday 12 March 2008 18:26:36 Ralph.Grothe at itdz-berlin.de
wrote:
> > # pvs
> >   /dev/drbd0: open failed: Wrong medium type
> >   PV         VG     Fmt  Attr PSize  PFree
> >   /dev/md1   vg00   lvm2 a-    9.54G 3.91G
> >   /dev/md3   vgdata lvm2 a-   27.94G 9.44G
> >   /dev/md5   vgrh   lvm2 a-    9.54G 3.91G
> >
> >
> > Oops, I wonder if "Wrong medium type" only disappears when
drbd
> > is completely shut down on this node?
> 
> Because when DRBD is in Secondary mode, "wrong medium type" 
> is what the kernel 
> tells you when you attempt to access the device. When DRBD is 
> shut down, its 
> block device nodes disappear and LVM doesn't scan them to begin
with.
> 
> Cheers,
> Florian
> 
> -- 
> : Florian G. Haas 
> : LINBIT Information Technologies GmbH
> : Vivenotgasse 48, A-1120 Vienna, Austria
> 
> Please note: when replying, there is no need to CC my 
> personal address. Replying to the list is fine. Thank you.
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> 



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