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Here is the PDF document I am referencing:
http://www.ultramonkey.org/papers/lvs_jan_2004/stuff/lvs_jan_2004.pdf
In the abstract, Horms makes a reference that the "throughput of the
cluster is limited by that of the linux director", which implies that by
using active-active LVS, you can move beyond this limitation.
Even if you put a 10GigE in front of each LVS, the LVS's physical
interface can only accept 1Gbit of traffic in. I believe the problem
with this whole design is the need for iptables to select what traffic
is handled by the individual LVS. Since iptables works at the kernel
level, you're limited by the physical interface in the LVS. Sure.... if
iptables saw a 2Gbit stream of traffic, it could probably drop the
un-needed half, but the traffic has to get to the kernel first and that
isn't happening through a 1Gbit link.
I really hope someone can shed some light on this. I would like to use
LVS for a special project, but it might not work unless I can use
active-active to double my throughput (will also be using bonded Gig-E
for a theoretical 4Gbit max). I'm currently using 2 LVS pairs at a
fairly decent-sized web hosting company and they're doing awesome.... so
i'd love to use them for this special project if possible.
---
Michael Spiegle
mike@xxxxxxxxxxxxxxxx
Joseph Mack NA3T wrote:
> On Thu, 2 Nov 2006, Michael Spiegle wrote:
>
>> I did some reading on active-active and while I think its a great idea,
>> I didn't quite understand how it was capable of doubling the throughput
>> as mentioned in the PDF document.
>
> Horms would be the final word on the matter, but he seems to be busy
> (hasn't popped up on the mailing list for a few weeks). I haven't read
> the Saru docs for a couple of years and you seem to have read them
> thoroughly and I assume you've got it right.
>
> n active directors can handle n times the bandwidth, but you have to
> send it to them. You'll need 10GigE (or something like that) in front
> of them.
>
> I didn't know that the directors had iptables rules infront of them to
> divide the work load. One of the requirements is to load balance and
> handle failover, so there must be at least two directors capable of
> handling any particular stream of traffic.
>
> Joe
>
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