[DRBD-user] drbd and LVM -> always getting duplicate volumes (was: can't use LVM2 on drbd devices)

Tomasz Chmielewski mangoo at wpkg.org
Tue Jan 15 09:52:13 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.

Lars Ellenberg schrieb:

>>> you did hear about udev and scsi id, did you?
>> For iSCSI, true, I could use a link like /dev/iscsi/blah -> /dev/sdX and 
>> put that /dev/iscsi/blah as a filter for lvm.conf.
>> dm-crypt devices don't have any ID or anything unique (that I know).
> you are supposed to be able to pass wanted major/minor numbers to
> dmsetup. lvm e.g. is able to provide "persistent minors"
> (persistent major theoretically only "mostly", not strictly, with kernel
> 2.6, though for al practical purposes I found that to be good enough,
> you get the same major anyways)

All right, once I figure out how, I'll keep the list updated.

>> 2. On system startup, find out which one of /dev/dm-XY devices is our 
>> crypted device. How to do it? If the device has unique size, just parse 
>> the output of fdisk -l. If there are multiple devices with the same 
>> size, it gets problematic.
> you could also use dm-crypt on top of drbd,
> instead of below it? I guess that would be the easiest way.

Indeed, but not in this setup.
Here, the whole disk is encrypted, but only a part of it is replicated 
with DRBD.
Of course I could partition the disk into parts encrypted separately, 
but then it's harder to maintain.

Thanks for all ideas.

Tomasz Chmielewski

More information about the drbd-user mailing list