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Hi There,
I'm having a hard time understanding how heartbeat could be a useful
program in a large load balanced situation. It is my understanding that
it establishes a serial connection, and a 'real' ethernet connection.
When the 'real' ethernet connection dies, heartbeat then instructs the
machine via the serial link to shut this or that down, then proceeds to
take its ip over.
A couple things bother me with this, and maybe i just havent read
enough, but it doesnt make a whole lot of sense:
1. Does this mean now that if I have 50 realservers that I need to buy a
50 port serial port device to connect cables to all of these? Sure, I
could use two ethernet devices as well. That would solve that, I
suppose.
2. Why does heartbeat have the responsibility of starting and stopping
the services? Does it really matter to stop apache if the machine is
dead? I mean, nobody's accessing it anyways!
3. When the director takes the IP over, what problem does this solve? If
i was using simply mon, or ldirectord, why not just remove the IP from
the list of realservers and get on with life? Consider machine (X) dead,
instead of making machine (Y) _look_ like machine (X).
I guess my question is: I assemble a server farm of http servers. I use
LVS to balance my load. Lets say I have 5 webservers and one director.
When machine 2 goes down, I can remove it from the list of realservers,
and the remaining 4 servers can deal with the load. When machine 2 comes
back up, I can enter its IP address back into the realserver table.
Confused,
Dayton.
PS. Any response to clarify what I believe to be me misunderstanding
Heartbeat would be so greatly appreciated, its turning to be a rather
large painful game of 'what do i use to ensure my users always get a
response, and fast'
:)
--
`~ ~'
O.O
---------------------------UUU-V-UUU---------------------------------
Dayton Turner UNIX Systems and Network Administrator
E-Mail: turnerd@xxxxxxxxxx Cell: (604) 809-7742
WWW: http://www.turnerd.com Richmond, BC, Canada
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