[rabbitmq-discuss] Portability of mnesia and other data between IP addresses

Fri Apr 15 18:16:42 BST 2011

It is the full Erlang node name that is stashed in the mnesia structures.
This is set either via the -name (uses full hostname) or -sname (use only
local machine name) erl command line option. So it'll depend a bit on what
your rabbit configuration/startup scripts say.

One way of making a particular Erlang node with mnesia easily relocatable is
to specify -sname myname at localhost, explicitly overriding the local machine
name by using localhost. This obviously only works if you're not doing
anything distributed, like clustering.

Robby

On Fri, Apr 15, 2011 at 11:35 AM, Alext0 <althomas at maninvestments.com>wrote:

>
> Thanks Simon, that's good news.
>
> This did come from a reputable source (!) - perhaps it applies to clusters?
> I mentioned mnesia, but of course we don't want any file to be "pinned".
>
> We'll probably ask for some confirmation that this is the case (and will
> hold for future releases) via official channels so that we have confidence
> our disaster recovery plan is valid.
>
> cheers
> Alex
>
>
> Simon MacMullen-2 wrote:
> >
> > On 11/04/11 15:18, Alext0 wrote:
> >> OK, a query with almost the same subject was posted a while ago!
> >>
> >> But that concerned clustering, DRBD etc, and our scenario is much
> >> simpler...
> >>
> >> We want to migrate an RMQ instance from one machine to another by
> >> stopping
> >> it, transferring the data files and restarting it at the destination.
> >>
> >> Externally, the DNS hostname is migrated from one IP address to the
> >> other.
> >> Our RMQ nodename will use the DNS name (e.g. RMQ1 - not a FQDN) so this
> >> won't need to change.
> >>
> >> Despite this, we heard there might be references to the IP address in
> >> mnesia
> >> files and hence migrating the IP address too would be required (i.e. we
> >> need
> >> a VIP) - can we get away without this?
> >
> > I don't believe Mnesia embeds IP addresses (where did you hear that?).
> > You should be fine.
> >
> > Cheers, Simon
> >
> > --
> > Simon MacMullen
> > Staff Engineer, RabbitMQ
> > SpringSource, a division of VMware
> >
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> > https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss
> >
> >
>
> --
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