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On Fri, Nov 10, 2006 at 02:06:30PM +0100, Roberto Nibali wrote:
> >>>I just just built 2 fresh gentoo boxes for testing active-active. I had
> >>
> >>How is active-active possible
> >it's Horms experimental code called Saru. He explained it at OLS one year
> >you
> >didn't come.
> >http://www.ultramonkey.org/papers/active_active/active_active.shtml
>
> Downloaded and printed, will read this weekend. Although, if Horms
> engineers something it's most likely flying anyway. So I just have to
> understand how he cheated the TCP stack this time :). I see some
> netfilter related stuff in it and I wonder if (from what I've seen)
> his approach works for 2.6.x kernels with proper TCP state tracking,
> TSO and USO? In 2.4.x where netfilter is mostly broken with regard to
> TCP state tracking, such quirks might be possible.
It is only active-active for the linux-directors, and its not really
supposed to be active-active for a given connection, just for a given
virtual service. So different connections for the same virtual service
may be handled by different linux-directors.
The real trick, is that it isn't a trick at all. LVS doesn't terminate
connections, it just forwards packets like a router. So it needs to
know very little about the state of TCP (or other) connections. In fact,
all it really needs to know is already handled by the ipvs_sync code,
and that mainly just a matter of association connections with real
servers. Or in other words, the tuple enduser:port,virtual:port,real:port.
--
Horms
H: http://www.vergenet.net/~horms/
W: http://www.valinux.co.jp/en/
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