Re: Database recommendations?

Ilan Berci
Thu, 22 Feb 2007 18:28:41 -0000

Paul Butcher wrote:

> Our issue isn''t performance - it''s reliability.
>
> We currently have a master/slave setup, where the slave is primarily
> intended for failover in the event of the master failing. We''ve
had a
> couple of occasions where the replication has failed recently for
> reasons we are currently unable to diagnose (the master has continued to
> run just fine, but the slave has crashed). Reestablishing the
> master/slave relationship requires that the slave has a perfect copy of
> the database, which means disabling our application in order to create a
> consistent dump of the database on the master.
>
> The last time we had to do this, it took around 10 minutes to perform
> the dump, which meant 10 minutes downtime. We run a 24/7 service, and 10
> minutes downtime is unacceptable. And our database is growing
> exponentially - we expect that the same operation in 6 months time is
> likely to take an hour - an hour''s downtime would be a complete
> disaster!
>

>
> Sorry for the less-than-entirely-clear inital e-mail!
>
> Thanks,
>
> paul.butcher->msgCount++

Paul,

I think your real problem is trying to diagnose why your slave is
crashing before you assume that you are running up against the upper
limits of MySQL replication.  What are the details of your master/slave
setup?, (a)synchronous?, distributed query load to slave?,
auto-generated keys? load?.

If money is no object, and your DBA is either not present or incompetent
then do yourself a favor and hire a DBA(s) to get at the cause of your
problem before you go through migration/portability/driver hell and save
yourself a wad of cash.

It should be fairly straight forward to look at the db logs on the slave
to see the last statement that went through before the crash..   I also
guess it''s obvious to assume that your slave is a dedicated db server..
right?   Is the crash dependant upon load?

I feel your pain and I have been there..  good luck

ilan



--
Posted via http://www.ruby-forum.com/.