On 06/09/11 2:45 AM, Sanjay Rao wrote:
Hi,
If anybody have setup this thing earlier or have any idea about how to
setup this, Please let me know. I am newbie in setting up database
servers .
frankly, for high availabilty first thing I'd do would be to take
windows out of the picture, it just complicates everything.
two general approaches to a high availability database server.
1) shared storage, with an active-standby pair of servers, managed by
some form of cluster management software like Linux Heartbeat, Redhat or
Veritas Cluster Service, etc etc. each server has its own IP, then
the active server has the 'server' IP that clients connect to.
active server has storage mounted, standby server is 'fenced' (usually
done via a SAN switch) so it can't accidentally mount the storage thats
in use. on failover, the formerly active server is fenced, the
standby server is unfenced, mounts the storage, takes over the shared IP
and starts the database service. clients see this as a service
interruption, usually lasting a few seconds to a half minute, they
reconnect when the former standby is ready and alive.
2) replication. active server is replicating data to the standby
server. the rest of the failover scenario is similar minus the
shared storage part. unless the replication is synchronous, there is a
possibility of losing the last few transactions if the master hard fails.
in general, high availability clusters are complex, delicate beasts,
require careful attention to the details, and once working, should NOT
be messed with except extremely carefully. an absolute bare minimum
should be running on the database servers so as not to complicate things.
--
john r pierce N 37, W 122
santa cruz ca mid-left coast
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