Hi
i'm using MySQL version 4.0.20d.
I was able to set up a simple replication between a master and a slave.
To fully understand the replication mechanism of MySQL i would like to ask
some questions (the manual does not answer all my questions):
(a) in 4.0.20d there is no way for a kind of Master-Master replication,
means, that both databases replicate to each other, right?
(b) Will there be such a feature in Version 5 (and does anyone know when it
is planned to declare version 5 as stable and productive)?
(c) Or is clustering a kind of Master-Master replication?
(d)Is it possible to have a MySQL database server being Slave of a Master A
and serving as Master for a Slave B at the same time and for the same
database?
(e) When i have a Master-Slave replication, what happens when i delete a
replicated record on the Slave - will the record than be replicated again or
will the record "remain" deleted?
So far my questions and i'm aware that some of them sound quiet wired, so i
will try do explain what i'm trying to do:
I have an application that runs on a server using a MySQL database that is
also installed on that server. Besides i have the same server with the same
configuration as a hot standby in case of something bad happens to my first
(productive) server. Let's refer to them as Server A (active) and B (hot
standby).
Both servers have a public Network interface and a private Network
interface. On the public side, they have the SAME IP Address. To avoid
collisions, the are connected to a managed switch where only the port to
Server A is active and is switch to port to Server B in case of emergency.
On the private Interface both servers carry a own, unique private IP
Address.
Since Server B acts as hot standby, it's database should always be up to
date, so i planned to use replication between Server A and B. A would act as
Master, B as Slave. So far, so good.
Now there is a third MySQL server (let's call it C) at a different location
(interconnection by a VPN over the internet). This server needs the data
from a table of my database in "almost-realtime". So i thought, replication
would be a good mechanism to do that. Now there are some problems:
(a) I know how to setup a replication A Master, C Salve, but what happens if
A goes down and we have to switch to the hot standby B? B is configured as
Slave in relation to A, so C would not be able to get Data from B. Is there
a way to setup a Master-Slave relation from B to C so C could replicate the
same data from B as it did before from A?
(b) The Application on Server C is going to delete records that have been
replicated. What happens then, will C replicate the deleted records again or
will they "remain" deleted on C? On A or B they should never be deleted,
regardless of what is done on C?
(c) After an case of emergency when i want to bring A up again and let it
server as active Server again, how would i be able to "replicate" the
records that have been created on B during the absence of A? At the moment,
i see no other way as to do this manually, as long as there is nothing like
Master-Master replication. Any other ideas?
Maybe i'm on a totally wrong track, maybe all some of you cracks out there
have a better idea how to solve this? Would clustering be such a solution?
Are there any other kind of synchronisation/replication tools that would
allow me to setup a configuration as needed?
I'm very thankful for any kind of support.
Thanks a lot
Frank
