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Hii
Just some clarity: are we talking about HTTP services or any
arbitrary service ?
Ideally one's hosting facility should be multi-homed and dealing with
route redundancy at the BGP level. Clearly this is not an option in
the cases under discussion.
I really don't see this as an issue that LVS is suited to. The
simplest possible solution to this issue as I see it is:
1. Co-host or host a server at a multi-homed (no single route failure
will render it unreachable) facility with redundancy ala heartbeat
(www).
2. the servers which will actually do the work are hosted elsewhere
at multiple cheaper facilities perhaps, without the required route
redundancy (www1, www2).
3. mon on www monitors the availability of www1 and www2.
4. ALL incoming HTTP requests are initially directed to www which is
always available. one only need issue this URL to one's clients.
5. www simply issues a HTTP header redirect either to www1 or www2
according to their health/ redirect count.
6. after the redirect the HTTP client continues to access the server
it was redirected to.
7. database replication can be handled over VPN between www1 and www2
if necessary. this has its own issues, but is doable.
Is this not a workable solution ?
Nick
On Thu, May 01, 2003 at 11:48:33AM +0100, Graham D. Purcocks wrote:
I saw something on the UltraMonkey site which did this, Super Sparrow. I
also found another, but not being too helpful, I can't remember the
name. However, both projects appeared to start in 1999 and don't appear
to be be actively developed. Both were Dynamic DNS solutions.
I have the same situation where we have ultra critical Web servers in
the UK, and mirrored in the US. We currently give out clients both URL's
but it would be nice to not have to do this.
So if anyone knows of a solution which is active, I also would be
interested.
I did a lot of work on Super Sparrow a while ago. But there han't
really been enough interest in it for me to do much work on it since.
The System that I designed (see www.supersparrow.org) is pretty simple
and works by using BGP data to determine the answer to DNS requesets.
It is also possible to use other sources to generate the answere too. I
actually wrote a very primitive back end that works of a static table.
This is the way that www.linuxvirtualserver.org is load balanced.
--
Horms
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