[CentOS] Warm standby server with rsync

rado rado at rivers-bend.com
Wed Mar 8 09:46:01 UTC 2006

On Wed, 2006-03-08 at 20:15 +1100, Nick wrote:
> I'm trying to mirror a live server onto a slave server of identical
> hardware. Theory being that when the master server blows up I can change the
> IP of the slave, restore the db's, restart a few processes and make everyone
> happy again.
> What is the best way of doing this? Can you literally rsync / (with the
> exception of perhaps /proc and /tmp) and create an identical copy of the
> master? Is there a better way to achieve this?
> I've looked at using cluster suite but I don't think the instant(ish) and
> automatic failover justifies the cost of the shared storage.
hi nick,

kk I'm doing exactly what you are trying to accomplish I think.

say the power went off completely.... nothing

k...comes back on...
I run the exact same daemon and scripts in 2 mirror machines.
I run the daemon in the first machine...it does the checking, realizes
the other machine is not serving so it takes the roaming ip address and
runs w/it. Then I run the daemon in the other machine...it realizes that
the other box has the ball so it assumes slave responsibilities which
are to just keep checking on the master...if the slave sees where the
master is having problems, it takes the roaming ip and runs with it.

while all this is going on...the master keeps syncing up the slave oh,
bout ever 15 seconds... Not perfect like a big $$$$ real time warez but
it's close enuf for a small place like this!

I'd say when the slave does take the ball...the whole process takes bout
30-40 seconds which I don't like but that's life... the router has to be
flushed one way or other in the deal...that's bout 20 seconds on this
cheepie I got because I have to warm boot it...but this whole process
w/all it's shortcomings on the time deals works flawlessly tho.

John Rose

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