On May 26, 2006 13:39 +0200, Anselm Strauss wrote:> does anybody know if for an oss tcp connections are always made
> towards it, or does it also happen that an oss makes connections itself?
Yes, in some cases it is necessary for OST->client connections to be
established. This can happen if the TCP connection between the client
and the OST is lost and the OST needs to send a message like a lock
cancellation.
> this would be important for the following scenario: with linux
it''s
> possible to have 2 network interfaces with 2 different ips on the
> same network and balancing traffic over both interfaces. the advanced
> routing option in the kernel allows one to define routing rules that
> make traffic coming in on one interface is always replied on that
> same interface. but connections initiated by the host will still go
> over only one interface.
We''ve found the performance poor when multiple interfaces are on the
same
subnet. As you mention, incoming traffic can be balanced for multiple
interfaces on the same network, but outgoing traffic generally takes the
same interface even if the source port specifies another interface.
Instead, CFS recommends TCP channel bonding for such configurations,
as the kernel bonding driver will balance the outgoing traffic over
all bonded interfaces.
In some kernels this requires a patch to the bonding driver
to fix the hashing function, and setting the module parameter
"xmit_hash_policy=layer3+4".
Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.