[Date Prev][Date Next] [Chronological] [Thread] [Top]

Re: explain diff between multimaster and mirror mode

On Sun, Jul 20, 2008 at 10:52 PM, Liutauras Adomaitis <liutauras.adomaitis@gmail.com> wrote:
On Fri, Jul 18, 2008 at 11:24 PM, Jorge Medina <jmedina@e-dialog.com> wrote
In MirrorMode, you still have two masters replicating to each other, but
you use a third component -the load balancer- to redirect all requests
to only one of the masters. If this master fails, then it switches to
the other server. Seems to me that the masters are aware of this
configuration because of the directive "mirrormode on"

So in MultiMaster configuration we have simply masters with ability to read/write to any of them.
In MirrorMode we have masters with load balancer, which decides where to redirect all the writes.
Am I right?
If yes, then one Master in MirrorMode is "more master" than others. How do they decide which one is "more master"? Is it dynamically and changing from time to time? In that case I will never know were my writes are going to.
I have a situation, were I want to be able to do writes to both masters, but want ot be sure that in certain cases writes are done to that master and no the other.

I just read the other thread "how to configure multi-master" and Dieter Kluenter is saying:
"Multi-way replication and mirror mode are two different
aproaches. While ldap servers configured for n-way replication are
all visible and available by all clients and all allowing all
operations. Mirror mode is a sort of backup and standby system. Only
one ldap server should be visible and available, thus allowing write
operations, while the second ldap-server is in hot standby position,
and only available to clients if the first server fails."

So answering to myself - I think I was right, and the "more master" decision is made should be made by myself. So in MirrorMode one database is Master and the others are hot standby mirrors, which supposed to be availlable to clients only on first failure.

Thanks a lot
I think I understand now