[DRBD-user] Multiple Clusters

Helmut Wollmersdorfer helmut.wollmersdorfer at gmx.at
Fri Jun 4 10:01:51 CEST 2004

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

Jason Gray schrieb:
> I'm looking at creating a multi-clustered array server network for our
> production environment.  Is it possible to have 5,6,7..n servers clustered
> together (kind of like a token ring) to act as redundant arrays for each
> other?

DRBD is a two node cluster.
You can have something like this:

          Node1      Node2      Node3
          -----      -----      -----
drbd1    Primary    Secondary
drbd2    Secondary  Primary
drbd3               Primary    Secondary
drbd4    Secondary             Primary

> So, instead of having a Primary array I would have 5,6 or 7 "Primary" arrays
> that mirror each other across an isolated network ( say).

Not each to each.

You can build a "chain":

Situation 1:

          Node1      Node2      Node3
          -----      -----      -----
drbd1    Primary    Secondary  stopped

Then switch to Situation 2:

          Node1      Node2      Node3
          -----      -----      -----
drbd1    stopped    Primary    Secondary

This sort of switchover will take time, because Node3 needs to sync with 
Node2. In case of a full sync of e.g. 100 GB this will need _hours_.

Helmut Wollmersdorfer

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