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> > Michael McConnell wrote:
> >
> > You want to take advantage of the DUAL NICS in the real server to provide
> > additional redundancy.
> > Unforchunately the Default GW issue comes up....
>
> I assume you have boxes each with 2 NICs and you want the
> 2 NICs to be redundant. This is a reasonable thing to expect
> but I can't see any easy way to do it. The nearest
> related things are
This is really more of an HA issue than an LVS issue. He might
want to try the linux-ha-dev@xxxxxxxxxxxxxxxxxxxxxxxxx mailing
list, or http://www.linux-ha.org, but I am not aware of any
current IP/NIC drivers that will do what he wants.
> 1. channel bonding, where multiple NICs on a machine have the
> same IP and MAC address and are used for higher throughput.
> I read through 2yrs of messages on the beowulf mailing list
> about this last night and couldn't see anywhere where people
> allow this sort of setup to run after one card has failed.
> I presume it's not doable.
I think "not doable" is an incorrect statement - "not done" would
be more precise. For the most part, beowulf is about performance,
not HA. I know that Intel NICs can use their own channel
aggregation or Cisco Fast-EtherChannel to aggregate bandwidth
AND provide redundancy. Unfortunately, these features are
only available on the closed-source Microsoft and Novell platforms.
http://www.intel.com/network/connectivity/solutions/server_bottlenecks/config_1.htm
> Having 2 NICs on a machine with one being spare, is relatively
> new. No-one has implemented a protocol for redundancy AFAIK.
I assume that you mean both of these statements to apply to Linux
and LVS only. Sun has had trunking for years, but IP multipathing
is the way to go now as it is easier to set up. You do get some
bandwidth improvements for OUTBOUND connections only, on a per
connection basis, but the main feature is redundancy.
http://docs.sun.com/ab2/coll.647.2/IPNETADMREFMAN/@Ab2TocView?Ab2Lang=C&Ab2Enc=iso-8859-1&DwebQuery=IP+OR+multipathing&oqt=IP+multipathing
http://docs.sun.com:80/ab2/coll.539.1/UGTRUNKING/@Ab2PageView/604?DwebQuery=IP+OR+trunking&oqt=IP+trunking&Ab2Lang=C&Ab2Enc=iso-8859-1
Sun also has had Network Adapter Fail-Over groups (NAFO groups) in Sun
Cluster 2.X for years, and in Sun Cluster 3.0. Veritas Cluster Server
has an IPmultiNIC resource that provides similar functionality. Both
of these allow for a failed NIC to be more or less seamlessly replaced
by another NIC. I would be surprised if IBM HACMP has not had a similar
feature for quite some time. In most cases these solutions do not
provide improved bandwidth.
> The next question then is how often does a box fail in such
> a way that only 1 NIC fails and everything else keeps working?
> I would expect this to be an unusual failure mode and not
> worth protecting against. You might be better off channel bonding
> your 2 NICs and using the higher throughput (unless you're compute
> bound).
I would agree, with one exception. If you have the resources to
implement redundant network paths farther out into your infrastructure,
then having redundant NICs is much more likely to lead to improved
availability. For example if you have two NICs, which are plugged into
to two different switches, which are in turn plugged into two different
routers, then you start to get some real benefit. It is more complicated
to setup (HA isn't easy most of the time), but with the dropping prices
of switches and routers, and the increased need for HA in many environments,
this is not as uncommon as it might sound, at least not in the ISP and
hosting arena.
I am not trying to slam LVS and Linux HA products - to the contrary;
I am trying to inspire some talented soul to write a multipathing
NIC device driver we can all benefit from. ;) I make my living
doing work on Sun boxes, but I use Linux on my Dell Inspiron 8000
laptop (my primary workstation, actually - it's a very capable system).
I would recommend Linux solutions in many situations, but in most
cases my employers won't bite, as they prefer vendor supported
solutions in virtually every instance, while complaining about
the official vendor support.
--
John Cronin
Compnology, Inc.
mailto: `echo NjsOc3@xxxxxxxxxxx | sed 's/[NOSPAM]//g'`
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