[DRBD-user] partition issues

Lars Ellenberg Lars.Ellenberg at linbit.com
Thu Mar 16 18:42:33 CET 2006

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

/ 2006-03-15 19:08:19 -0800
\ Ben:
> I recently installed Xen on top of a DRBD block device. At first this seemed to go great, but now my xen guest seems to be having a hard 
> time finding its partitions. I thought I'd try to mount the partitions manually and see what's up, but low and behold, I cannot mount 
> them either.
> Xen is supposed to be looking at /dev/drbd2, so if I use fdisk to look at /dev/drbd2, I see:
> Disk /dev/drbd2: 31.4 GB, 31474057216 bytes
> 255 heads, 63 sectors/track, 3826 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
>       Device Boot      Start         End      Blocks   Id  System
> /dev/drbd2p1   *           1          13      104391   83  Linux
> /dev/drbd2p2              14        3826    30627922+  8e  Linux LVM
> So it *seems* like I should be able to mount /dev/drbd2p1 or /dev/drbd2p2. Alas:
> # mount /dev/drbd2p1 /mnt
> mount: special device /dev/drbd2p1 does not exist
> # mount /dev/drbd2p2 /mnt
> mount: special device /dev/drbd2p2 does not exist
> Why doesn't this work? Are there DRBD logs I can look at? /var/log/messages isn't giving me anything.

you cannot partition a drbd.  we don't support partitioning.
thats why those device nodes do not exist.

as for the output of fdisk: it "interprets" the start sector of the
block device, and "sees" a partition table there.
if you dd if=/dev/hda bs=512 count=1 > tmp.out, and point fdist at
tmp.out, it will see a partition table in there, too.
that does not mean that you could mount tmp.outp1 ...

maybe you can virtualize this problem away somehow in the xen guests.
I did not do too much xen yet, so I cannot recommend on that.

: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
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