Re: failover mirror - enbd good solution?

"Also sprach Tomka Gergely:"
> I need to setup two servers, one running mysql, the other apache+php. If
> one of the servers dies, then i need to run the two application on the
> survivor.

This is a standard kind of failover setup.  There are heartbeat scripts
do that in the nbd/etc directory of the enbd archive:

 % ls ha.d/
 -rw-r--r--  1 ptb  815 Dec 22  2003 haresources
 drwxr-xr-x  2 ptb 1024 Feb 20  2005 resource.d/

  
> I played with ENBD before (cca. 2 years), and as i recall, enbd is a good
> solution for the data-syncing.
> 
> My idea is a raid1 (fr1) between the two machine, mounted on machine A,
> and mysql running on the fr1 device. If machine A dies, then machine B
> stops the fr1, mounts the remaining half as a "half legged" raid1, and
> start the mysql on machine B.

The problem isn't really in the failover, but in reintegrating changes
reliably when the other server comes back up.  The scripts in the
archive are said to do that (I run a somewhat simpler setup myself, but
others developed those scripts ...).

Peter