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Joseph Mack PhD, High Performance Computing & Scientific Visualisation
LMIT, Supporting the EPA Research Triangle Park, NC 919-541-0007 Federal
Infrastructure Contact-Ravi Nair 919-541-5467 - nair.ravi@xxxxxxx,
Federal Visualization Contact - Joe Retzer, Ph.D. 919-541-4190 -
retzer.joseph@xxxxxxx
lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx wrote on 06/01/2005 01:33:56
PM:
> The part I do not understand is how to have a LVS cluster
> fail over without using HA. Since HA is limited to two nodes ?
There are several packages available to do failover
for LVS. Some of them overlap in functionality and
some of them are for different purposes. I'm not
surprised that there is confusion here.
The LVS can have an number of realservers. Failover
of realservers occurs by changing the ipvsadm table
on the director.
Director failover occurs by transfering the
VIP to the backup director, bringing down
the primary director, and by using the backup
copy of the connection table (put there by the
synch demon) on the backup director.
Director failover and realserver failover are
logically separate, occur independantly and
are done by different pieces of code eg
MON onlt handles realserver failover.
Since both functionalities are required in
a production LVS, some packages have
them both. When configuring these packages
you must remember that the director
failover parts are logically separate
from the realserver failover parts.
Both keepalived and Linux-HA handle director
failover and to monitor the state of service(s)
on the realserver. Keepalived has both
functionalities in the same piece of code
and uses one configure script. Linux-HA
uses ldirectod to handle realserver failover.
I think now that you set up Linux-HA/ldirectord
with one configure script (not sure).
Joe
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