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Manually. But it's never happened in real life, just in lab tests. A script
could be written to do it, I guess, but it's not that simple.
All the talk about redundancy and high-availability is a bit academic, IMO,
unless it really is mission-critical -- and if it was, I'd be using Oracle
and not MySQL so I could blame them. ;-)
As I mentioned, none of this matters if bandwidth and electricity go out,
which is less reliable in my experience than solid-state computer hardware.
But this is getting off-topic, maybe we should continue this in private
mail?
On 10/25/05, Mark <msalists@xxxxxxx> wrote:
>
> So let's assume your master goes down for whatever reason, and you have to
> make one of the other slaves a master.
> Do you do this manually, or do you have a script that detects the problem
> and acts automatically?
>
>
>
> > -----Original Message-----
> > From: lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx
> > [mailto:lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx] On Behalf
> > Of Troy Hakala
> > Sent: Tuesday, October 25, 2005 4:49 PM
> > To: LinuxVirtualServer.org users mailing list.
> > Subject: Re: Using LVS for MySQL traffic
> >
> >
> > That's true, but the master is redundant in itself (RAID
> > drives, redundant
> > power) to minimize the risk. But yes, we are very
> > read-intensive and keeping the master out of the read
> > load-balancing further increases the master's lifespan.
> >
> > We haven't tried master-master replication, but it's pretty
> > easy and quick to turn a slave into a master. We prefer
> > simplicity to complexity. Besides, we're not a bank and no
> > one dies if the master db goes down for a few minutes every 5
> > years. :-)
> >
> > FWIW, our outages have been caused by bandwidth outages more
> > than server hardware failure. There's supposed to be
> > redundancy there too, but for some reason or another, the
> > redundancy never kicks in. ;-)
> >
> >
> > On 10/25/05, Mark <msalists@xxxxxxx> wrote:
> > >
> > > But you only solve half of the problem - if your master
> > goes down you
> > > can not do write operations any more... Still better than
> > being down
> > > completely of course, especially if you have a higher percentage of
> > > reads compared to writes, plus you have the load-balancing if your
> > > reads are complex load-intensive queries.
> > >
> > > Did you ever try master-master replication? Some people use
> > that, but
> > > I think it's not totally trivial, there are some potential pitfalls.
> > >
> > > MARK
> > >
> > >
> > > > -----Original Message-----
> > > > From: lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx
> > > > [mailto:lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx] On
> > Behalf Of Troy
> > > > Hakala
> > > > Sent: Tuesday, October 25, 2005 4:28 PM
> > > > To: LinuxVirtualServer.org users mailing list.
> > > > Subject: Re: Using LVS for MySQL traffic
> > > >
> > > >
> > > > We're using master/slave replication. The LVS balances the reads
> > > > from the slaves and the master isn't in the
> > load-balancing pool at
> > > > all. The app knows that writes go to the master and reads
> > go the VIP
> > > > for the slaves. Aside from replication latency, this works very
> > > > reliably.
> > > >
> > > >
> > > > On 10/25/05, mike <mike503@xxxxxxxxx> wrote:
> > > > >
> > > > > On 10/25/05, Troy Hakala <troy@xxxxxxxxxxxxxx> wrote:
> > > > > > it works fine, we've been doing it for years. :-)
> > > > > >
> > > > >
> > > > > thanks :)
> > > > >
> > > > > okay, here comes the next question then... just for curiosity -
> > > > > for both of you guys.
> > > > >
> > > > > how are you replicating the data between mysql servers?
> > > > >
> > > > > NDB/MySQL clustering?
> > > > > master/slave replication?
> > > > > something else?
> > > > >
> > > > > thanks
> > > > > - mike
> > > > > _______________________________________________
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> > > > >
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> > > >
> > >
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>
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