On Jan 4, 2005, at 2:23 PM, Aristedes Maniatis wrote:
What are the specifications for your project? What level of downtime
can you afford to have? For example, if your backend database server
fails, is it OK to then switch over manually to a replicated database?
Do you have to use mySQL as per your initial statement?
As a start, I don't think mySQL can do what you want. Sure you can
mirror to a second machine (we do that), but in case of failure of the
primary you need a script to switch your instances to point to the
second database server. I don't know that that would be trivial.
Remember with this kind of setup, you can only write to one (master)
database. All the slaves are useful for read only (or if you take the
master offline and make another machine the primary).
I actually had a working master/slave site running.
There are three Xserves total, one of which is a cluster node. There
is the primary host running my WO Application and the MySQL master, a
secondary is the MySQL slave but does not run WebObjects. These two
servers are also configured for IP Failover.
The third is a cluster node running my WO Application using MySQL over
the network to the master.
When the master fails, OSX Server executes a number of scripts on the
slave (PreAcq*, PostAcq*).
These allow the slave SQL server to be reconfigured to stop being the
slave and start being a master, start WebObjects, Apache, etc. (The
primary and the secondary share the same wo site config file.)
When the primary server comes back, the entire database is sent back
from the secondary to the primary. WebObjects services, etc. are shut
down and the secondary becomes the salve again (PreRel*)
I am not happy with this configuration since it's possible to send
large amounts of data around when the master site is simply rebooted.
Also the JDBC drivers only talk to one MySQL server, no failover there
in case MySQL alone goes belly up.
I much rather have a WebObjectst/MySQL cluster with multiple MySQL
servers and multiple separate WebObjects hosts with jdbc failover. And
put a load balancing switch in front of Apache.
(Right now I seem to have trouble seeing a database, with tables in the
cluster, created on one MySQL server from another MySQL server in the
cluster).
Thanks for the comments.
On 05/01/2005, at 2:25 AM, Klaus Berkling wrote:
I am particularly interested in load balancing, using WO, DNS round
robin, or external monitoring/load balancing host.
IP failover for high availability? As look at different solutions I
always end up with a single point of failure.
-------------------------->
ish group pty ltd
http://www.ish.com.au
7 Darghan St Glebe 2037 Australia
phone +61 2 9660 1400 fax +61 2 9660 7400
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kib
--
Klaus Berkling
Systems Administrator
DynEd International, Inc.
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