[DRBD-user] Drbd and network speed

[Ralf Gross]

Christian Balzer schrieb:
> 
> On Wed, 16 Sep 2009 13:25:47 -0400 Fortier,Vincent [Montreal] wrote:
> > > -----Message d'origine-----
> > > De : drbd-user-bounces at lists.linbit.com 
> > > [mailto:drbd-user-bounces at lists.linbit.com] De la part de 
> > > Diego Remolina
> > > Envoyé : 16 septembre 2009 09:17
> > > > 
> > > > linux bonding of _two_ nics in "balance-rr" mode, after some tuning
> > > > of the network stack sysctls, should give you about 1.6 to 1.8 x the 
> > > > throughput of a single link.
> > > > For a single TCP connection (as DRBDs bulk data socket is), bonding 
> > > > more than two will degrade throughput again, mostly due to packet 
> > > > reordering.
> > > 
> > > I've tried several bonding modes and with balance-rr the most 
> > > I got was about 1.2Gbps using netperf tests. IIRC, the other 
> > > issue of balance-rr is that there can be retransmission which 
> > > slows down the transfers.
> > > 
> > > Any specific information or howto accomplish the 1.6 to 1.8 x 
> > > would be really appreciated.
> > > 
> > > I am currently replicating two drbd devices over separate 
> > > bonds in active backup mode (two bonds with 2 Gigabit 
> > > interfaces each using mode=1 miimon=100).
> > 
> > I've done some testing with 2 giga NIC's in different bonding modes and
> > balance-rr was the slowest one.
> > 
> > I'd love to know how to achieve that speed because the way it is now it
> > will most probably be active-backup or simply a single nic setup.
> > 
> I'd love to know how you managed that, seriously. It may be the type of
> NICs and kernel features like offloads that may or may not impair your
> performance here, but for me with 2 or in the current case 4 interfaces 
> balance-rr always scaled as expected and stated above.
> 
> balance-xor (note that this basically means one interface for a direct
> connected cluster) iperf results:
> [...]

I have the experience that balanced-rr can give you a better
performance for directly connected NICs. But is gets difficult if
switches with etherchannels are involved. I wasn't able to get the
higher bandwidth in this setup.

Ralf