[DRBD-user] Replication over a VLAN between two distant sites ?

Motoharu Kubo mkubo at 3ware.co.jp
Fri Oct 23 00:43:25 CEST 2009

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

My customer has been using remotely backup for years with 3-node setup 
but without DRBD Proxy AND DRBD>8.3.2 its usage was restricted. 
Recently it introduced both and remote replication became possible and 
it works greatly with effective 10Mbps line and avarage round trip time 
(measured by ping) 0.8ms.

> The subject says it all, is DRBD replication possible
> between two nodes at different geographical locations ?

If your WAN line has very good quality (broad bandwidth and low latency 
--- round trip delay) AND storage size is not so large AND protocol A is 
adequate, no DRBD Proxy would be required.

DRBD Proxy can compress packet contents and it offers large buffer.

If your storage size is large (my customer's case: 1TB) when connection 
is made first phase of DRBD (exchanging bitmap) took more than few 
minutes and during this phase all disk write is suspended with DRBD < 
8.3.2.  Using use-rle option (DRBD>=8.3.2) it shortened to less second!

Best Regards,
Motoharu Kubo

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