[racktables-users] Re: Question about racktables and mysql Cluster.

  • From: "Michael Mansour" <mic@xxxxxxxxxxx>
  • To: racktables-users@xxxxxxxxxxxxx
  • Date: Sat, 11 Jul 2009 14:33:00 +1100

Hi Jonathan,

> > Hi,
> >
> > > Good Day everyone,
> > >
> > > I am interested on putting racktables on a mysql cluster.  Is anyone
> > > doing this now?  Did you have to do anything special?
> >
> Is this because you have a MySQL Cluster, or you need Racktables to 
> run in some sort of HA configuration?
> I am not running Racktables on MySQL Cluster, but I don't see 
> anything obvious to prevent it.  I wouldn't create a new cluster 
> specifically for Racktables though.  If you have one already, then 
> it might be worth testing.
> > > From what I read so far (an it is not much) you need to change the
> > > engine to ndbcluser.
> >
> I don't have access to a test MySQL Cluster right now, or I would 
> try it.
> >
> > This depends on how you're intending to cluster MySQL. There are many ways
> > to
> > do this using Linux HA software or through MySQL clustering/relication
> > systems.
> >
> > Personally if I was doing this I'd use software like linuxha.net to make a
> > MySQL cluster app, and then tell Racktables to use that MySQL instance via
> > a
> > hostname or IP address.
> >
> I can think of three options in order of complexity (most to least): 
> MySQL Cluster, MySQL / DRBD, MySQL Multi-master / Virtual IP.
> MySQL Cluster requires at least 3 servers just to run the database 
> (if you want any type of HA).  There are lots of things to think 
> about, like all indexes are stored ONLY in RAM (as is ALL data by 
> default) which can be rather limiting if not engineered correctly.

Yeah, it sounds like for that you need pretty good DBA skills.

> A MySQL/DRBD option is also somewhat tricky to get going if you haven't
> before.  It does require less hardware (2 servers) and no 
> modifications to the tables.  If you can be tolorent of a few 
> seconds of downtime if a node fails, then this should work just 
> fine.  You would have to write a script to launch MySQL on the 
> failover node too.

It's been years since I was "new" to linuxha.net but even then I didn't really
find it hard to get going, and the years since it's just gotten easier.

I currently run five linuxha.net clusters (most with MySQL HA'ed in them) and
another three for clients. The most recent linuxha.net cluster I built HA's
XEN guest's and I found that easier to setup than actual cluster apps (which
need file syncing and scripts between nodes). Because the XEN guest is
self-contained, there's not much to it apart from bringing it down on one node
and up on another.

> MySQL Multi-master would let you update to either server, and only requires
> 2 servers.  It could also be more geographically redundant (except 
> for the shared IP, but you could get around that by using a load 
> balance like Pirahna in front).  This type of replication is 
> asynchronous and you could lose data.

That's something I've always wanted to "try" just out of interest but if
there's the possibility of losing data? hmm.. maybe not.


> Hope that helps.
> -Jonathan
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