[DRBD-user] DRDB three-node cluster variant

Lars Ellenberg lars.ellenberg at linbit.com
Sat May 17 21:04:09 CEST 2014

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

On Sat, May 17, 2014 at 01:14:58PM -0400, Steve Thompson wrote:
> Is it possible to configure a three-node DRBD cluster where the
> third does *does not* have any storage, and is primary in the sense
> that it is the target of I/O from clients (which it then forwards to
> *both* storage nodes across the network)? I know that I could build
> a two-node DRBD cluster and export the block device as an iscsi
> target, but that's not what I'm after.

In theory, you can

[Diskless DRBD] ----- [Stacked DRBD]     [Stacked DRBD] ----- [Diskless DRBD]
                      [ Lower DRBD ]-----[ Lower DRBD ]

And as long as all links are up,
you could have them all be primary,
and put some OCFS2 or GFS2 on top of all four nodes.

Performance may not be what you'd like,
and will likely be worse on the "detached" leaf nodes.
But I don't know, never attempted something like that.

Should work fine as long as nothing breaks.

Thinking through failure scenarios,
and how to best deal with them,
is left as an excercise ;-)

Would that come close to what you think you want?

Or contact our LINBIT USA guys to talk it through...
Maybe that's finally the killer application
for dual-primary and stacked mode ;-)


: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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