[Linux-cluster] mysql and redhat cluster suite?

Brenton Rothchild brentonr at dorm.org
Fri Dec 16 23:10:54 UTC 2005

I think the MySQL Cluster product and what I was describing
were two different things.

I wasn't talking about using the MySQL Cluster product,
just running regular MySQL on two separate RHCS nodes
that have a shared GFS filesystem.

It appears that the MySQL Cluster system, from what I
can find, is more like a network-aware locking mechanism
at the MySQL layer that works only with in-RAM databases.
It also looks like you need a front-end SQL node to sit
in front of the two (or more) server nodes, an administration
node, etc.

Overall, the MySQL Cluster system looks like a stand-alone
cluster product, whereas I was trying to say that I was
going to run two normal MySQL processes on two RHCS nodes,
which from a different perspective could be seen as running
two MySQL server instances pointing at the same datadirs
using flock() to lock between them.

Since GFS makes flock() cluster-wide, and this appears
to be the only arbitration between multiple MySQL server
instances, then GFS would allow multiple MySQL server
instances to run on different nodes just as running
on the same machine.

I see several advantages over MySQL Cluster to running this
way - less number of dedicated MySQL nodes (no Admin,
SQL nodes, etc.), it integrates into an existing RHCS
arrangement, and, of course, cheaper due to not purchasing
MySQL Cluster.

There are several disadvantages, such as no query caching
and it's not all in-RAM (speed-wise, although not committing
to disk that often is another issue...).

Does that explain what I was trying to get across a bit
better?  I still don't think I'm entirely off my rocker,
but I've done so before :)

-Brenton Rothchild

gwood at dragonhold.org wrote:
>> Anyone feel free to correct me, but I was just doing some
>> reading on active-active MySQL + GFS last night, and
>> I think such an arrangement might be possible to a degree.
> http://dev.mysql.com/doc/refman/5.0/en/mysql-cluster-overview.html
> "MySQL Cluster is a technology which enables clustering of in-memory
> databases in a share-nothing system."
> So I'm not sure what you're hoping to achieve... The on disk storage needs
> to be unique to each machine - and the data needs to all fit into memory.
> Unless I'm missing something?
> --
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> Linux-cluster at redhat.com
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