[Beowulf] Channel bonding, again

Jan Heichler jan.heichler at gmx.net
Fri Oct 12 14:42:37 EDT 2007


Hallo Henning,

Freitag, 12. Oktober 2007, meintest Du:

HF> Hello Greg,

HF> On Thu, Oct 11, 2007 at 03:13:16PM -0700, Greg Lindahl wrote:
>> I'm thinking about using "balance-alb" channel bonding on a
>> medium-to-large Linux cluster; does anyone have experience with this?
>> It seems that it might generate a lot of arp replies if a switch
>> fails.
>> 

HF> We did some experiments with channel bonding.

HF> The bond device inherits the MAC-address of the first
HF> interface, meaning, it comes with a single MAC- and a single
HF> IP-address.  The bonding mode determines the load-balance of the
HF> transition.

That is not 100% correct. There are at least 6 mod that the bonding
device of linux supports. balance-alb and balance-tlb are not
assigning the same MAC to the interfaces in the bond. Therefore you
don't need a switch that supports trunks or something similar.

The problem ist that the performance of the bonding device under linux
is far away from being optimal (as far as i saw). The round-robin or
ad modes do not bring more than 140 to 150 MB/s out of 2 Gigabit
links.

The load balancing modi allow multiple connections to be fast but are
not speeding up a single connection (each connection is limited to the
speed of a single link in the bond). As a second point the balancing
modes create a heavy load on the nodes and can interfere with a
parallel computation.

Regards Jan

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