[DRBD-user] DRBD9 Satellite nodes

Roland Kammerer roland.kammerer at linbit.com
Thu Apr 21 18:07:53 CEST 2016

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


On Thu, Apr 21, 2016 at 05:41:40PM +0200, Dietmar Maurer wrote:
> > - it accesses the drbdmanage control volume, which is a drbd resource
> >   itself, and where the cluster information is stored, via TCP/IP. The
> >   reason satellites exist is that currently a drbd volume is limited to
> >   32 nodes. As the cluster information is stored on a drbd volume, that
> >   would limit the whole cluster to 32 nodes. That is avoided with
> >   satellite nodes that get their cluster configuration via TCP/IP, so
> >   you can keep adding a lot more than 32 nodes to you cluster.
> 
> What happens to a satellite node if the corresponding control 
> node is offline? 

On startup the satellite node just waits for a connection. If the
connection breaks, the satellite detects it and waits for a new
connection. Can be the old control node or a new one (assign-satellite).

> Why is there single a dedicated control node?

Because it is the mode that is the easiest to implement. Which control
nodes qualify to be the control node for a particular satellite? All?
The ones in the same site? The ones with the best
$insertyourfavoritenetworkingterm? Plus some minor, usual considerations
about determinism of the heuristic and locking.

Patches welcome...

Regads, rck



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