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Hello all,
We (the system admins of a national french research center) currently have a
machine hosting 3 essential services : DNS, mails (SMTP+POP) and HTTPS.
We'd like to improve the availability level of these services by sharing
(duplicating) them onto 2 redundant machines (strictly identical machines).
Ideally we are looking for a supervisor-program, set up on the 2 machines (let's
name them A and B), and having a privilegied link allowing them to know in
real-time which one is active (the main director).
This program would forward indiscriminately tasks to A or B.
In fact we have noticed (carefully reading the HOWTO & mini-HOWTO) that this is
what LVS provide, but we'd like to have only 2 machines in addition to the
clients, that is to say A would merge the functions of main director and
realserver #1, and B would be the backup director and at the same time the
realserver #2.
Is it possible to have this topology using LVS (possibly with heartbeat, fake,
mon, ...) or with another vitual server ? Or is this topology absolutely wrong
or impossible ? Do we need 4 machines for HA and load balancing _BY SERVICE_ (we
don't want to swap entirely on B, short-cutting A, if only a service fails on A.
The 2 others still working stay active on A and only the one failing on A
becomes supported by B) ?
Many thanks for any response/hint !
Best regards,
Laurent.
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