On Tue, Aug 06, 2002 at 02:07:15PM +0100, Robert Davies wrote:
> On Tuesday 06 August 2002 13:24, you wrote:
>
> > I did it for an Architect in London on a contract, but might try it at
> Cool :)
I've played around with this stuff too.
> > Issues with certain software meant it was less effective as I could only
> > bond two cards and the third one had to go back to being a single channel.
>
> Did the throughput double? Was there any impact on latency?
> Was it kernel software, or applications and briefly what kind of issues?
As Jon said: enable bonding in the kernel config and then you also need
ifenslave which sets up the bonding. You also need patience as if you're
trying to set this up between headless boxes you can easily bugger up
various things requiring reboots to be able to recontact your boxes!
Performance does not double. It maybe worth trying this with the kernel
pre-empt patches and other high performance patches. I only found about
a 25% improvement over single X-over. OTOH, I'm using fairly cheap NICs.
If you're using 4-port server NICs then things may be rather different.
The man page for ifenslave suggests that it's possible to retain the
separate IPs of the NICs in addition to having the bonded IP. However, I
could not get this to work at all: instead I use ifenslave -E which
forces the NICs onto the same IP.
> > > Were the channels put through a switching hub, or simply created a
> > > private dedicated network using X-over cables? Are there any gotchas you
> > Through a switch configured in trunking mode.
Here I've got it through 2 X-over cables. Not played with switches for
this.
> > Nope, you don't make them "visible" in that sense, they're bonded.
>
> OK, I guess I should read up on it, but I guess 'bonded' means you have a
> dedicated Point to Point fat pipe, using 2 NICs?
Yes, ifconfig will list your 2 NICs which 'appear' to have the same MAC
address and in addition a 'bond0' device which again has the same MAC
address.
> Well I'm considering utilising some spare ports on 4 port NICs, and
> remembered your project as something 'interesting', to look into when I got
> time. I guess the main question was if the time put into it paid off, and
> would you do it again, or insist on the Giga-Ethernet route?
It's a lot cheaper than Giga-Ethernet and is beneficial. If you really
need the extra bandwidth that GE provides then you have no choice, but
if you a) want a bit more bandwidth and/or b) want to reduce the
individual loads on your NICs then this is something to look at.
Matthew
--Matthew Sackman Nottingham England
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