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On Mon, 26 Feb 2001, Johan Isacsson wrote:
>
> Ok, here's another attempt:
>
> Location 1 (4 Mbit max)
>
> --------- Lan
> | FS 1 |---
> --------- | -----------
> ---| Router1 |
> --------- | -----------
> | FS 2 |--- |
> --------- |
> Internet------------------
> |
> |
> ------------
> ---| Router 2 |
> | ------------
> -------- |
> | VFS1 |----|
> -------- |
> | Lan
> -------- |
> | FS 3 |----|
> -------- |
> |
> -------- |
> | FS 4 |----
> --------
>
> Router 1 has a limit of 4 Mbit
> VFS1 is the virtual file server
> FS1-4 are the real file servers
>
> Basicly what i want is to load balance between the file servers but put all
> load on FS1 & FS2 until the bandwidth usage on Router 1 is up at 4Mbit, then
> start using FS3 & FS4 aswell. The load on this cluster is rapidly changing
> so it won't work to put static weigths in the scheduler (at low traffic
> Location 1 would be able to take all traffic but at high traffic 4Mbit isn't
> enough).
For this setup, you probably don't want to use 'VFS1' to distribute
traffic to FS1&2. A good way to handle two distinct internet presences is
to use a type of DNS weighted round-robin. You could either put another
LVS box in front of FS1&2, or just add them individually to DNS. The end
result would be two (or three) records in DNS for your cluster (VFS1, and
either a new VFS2 or just FS1&2).
With DNS weighted round-robin, you can use very short TTL for the records,
and use a monitoring program, in conjunction with Dynamic DNS Updates to
remove records for failed servers, or remove records when the traffic
maxes out at the secondary location. About a days worth of scripting. This
would very roughly approximate what Cisco Distributed Director does.
--
Michael Brown
Linux Systems Group
Dell Computer Corp
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