[DRBD-user] Question on ext3 and dual primaries mode

PieterB PieterB at gewis.nl
Sun Sep 13 19:57:06 CEST 2009

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


Hello,

I'm about to create a DRBD cluster with 2 disks per node. I want to use dual
primary mode, in order to be able to write to both nodes concurrently.

If I interpret http://www.drbd.org/users-guide/s-dual-primary-mode.html
correctly dual-primary-mode requires the use of a shared cluster file system
that utilizes a distributed lock manager, such as GFS(2) or OCFS2 filesystem. 

I was wondering if using ext3 is also possible when using dual primary mode.
The DRBD-docs seem to state that this is impossible. I was amazed, that
according to the Ubuntu server guide,
https://help.ubuntu.com/9.04/serverguide/C/drbd.html this seems a possible
setup. The example on that page uses "allow-two-primaries" and ext3 as filesystem.

Can you tell me if the Ubuntu page is wrong, or that it's (now) possible to use
ext3 with dual-primary-mode.

Is it also possible and recommended to use a LVM RAID0 as a DRBD source disk?
E.g. LVM2 RAID0 of 2 disks <-> DRBD <-> EXT3 | OCFS2 | GFS2

If using ext3 is not an option, which is preferable? OCFS2 or GFS2?

I'm using a Ubuntu 9.04 server, with the DRBD-nodes as virtual machines based on KVM.

I'm hoping somebody can answer my questions,
Regards,
Pieter




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