[DRBD-user] Supported bonding modes for drbd interconnect

Arnold Krille arnold at arnoldarts.de
Sat Sep 28 00:32:32 CEST 2013

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, 26 Sep 2013 08:33:02 +0000 Andreas Mock
<andreas.mock at drumedar.de> wrote:
> I couldn't find a definitiv answer for my question:
> Which ethernet bonding modes are supported for the
> DRBD interconnect?
> I found the following in 
> http://www.drbd.org/users-guide-8.4/s-prepare-network.html
> "[...] and the bonding driver (in active-backup mode) is recommended
> [...]"
> Does this mean: When you use the recommended bonding than you
> HAVE to use active-passive?

I did some experiments with bonding two 1G links. As expected
active-passive gives you fallback even when the two links go from
machine to two (interconnected) switches. With that you can wire both
nodes to both switches, interconnect the switches and get a setup the
works even if one switch or one cable stops working.
balance-rr only works on directly connected machine, switches get
confused about the mac-addresses hopping between ports. And then your
switches are so busy updating their arp-tables that they can't route
the data anymore.
When you really want to use two links from machine to switch to
machine, you have to use LACP so each component knows what to do.

In the end I stopped my experiments and choose active-passive bonding
across two switches for the main interface and balance-rr for the
direct 2x10G-link. Now its up to the various drbd-resources (~20 on
last count) to max out 20G bandwidth.

Hope that helps.

Have fun,

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