[DRBD-user] Using names instead of IPs in resource 'address' entries

Lars Ellenberg lars.ellenberg at linbit.com
Tue Sep 6 19:07:05 CEST 2011

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

On Tue, Sep 06, 2011 at 12:06:05PM -0400, Digimer wrote:
> I find myself setting up clusters in one location, then moving them to a
> second location which requires a new set of IPs. With the other cluster
> applications, this is not a problem because I can use resolvable names
> and update just /etc/hosts. However, this doesn't seem to be possible in
> Am I missing something obvious? If it is possible, please let me know.
> If it's not possible, may I ask why not? Would it be possible to request
> this ability as a feature request for a future release?

drbdsetup already does a lookup, and we likely will relax the parser to
allow hostnames instead of IP addresses as well "soon".

The basic problem: if the link goes away because of one node chaning its
IP, we cannot possibly do a dns lookup from kernel space...
Well, we could. But that would be a good reason to kick us out of the
kernel and never talk to us again ;)

So what you would need to do, if you expect the IP to change,
is to "periodically" run drbdadm adjust, just in case.
Or ask your cloud provider for persistent addresses...

If you do not expect the IP to change "at random", just wait a bit, as I
said this will likely show up as a "convenience" feature" in the near

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

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