[Linux-cluster] mysql and redhat cluster suite?

Vladimir Grujic hyperbaba at neobee.net
Mon Dec 19 11:03:29 UTC 2005

On Friday 16 December 2005 15:50, Brenton Rothchild 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.
>  From what I can read in the MySQL documentation,
> http://dev.mysql.com/doc/refman/5.0/en/system.html
> http://dev.mysql.com/doc/refman/4.1/en/system.html
> MySQL can use external file locking via flock() calls,
> although the 4.1 page describes that file locking is turned off
> by default "because Linux file locking is not yet safe" via
> a compile-time option "--skip-external-locking".
> The 5.0 page doesn't warn against using external file locking
> to that degree, but the option to use locking is still
> disabled via the "--skip-external-locking" flag.
> There are also some caveats to using the --external-locking option
> in MySQL.  See the documentation for "--external-locking" in
> http://dev.mysql.com/doc/refman/4.1/en/server-options.html
> http://dev.mysql.com/doc/refman/5.0/en/server-options.html
> Now, on the GFS side, locking via flock() and fcntl()-based
> locks appear to be supported cluster-wide from this thread,
> http://www.redhat.com/archives/linux-cluster/2004-October/msg00311.html
> So, putting them together, if GFS supports file locking,
> and MySQL can use file locking to support multiple instances
> accessing the same files, an active-active MySQL set up should work.
> I, too, and using a test cluster with GFS + iSCSI at this point,
> and I plan to test MySQL 4.x and 5.x versions on it soon to
> see what happens.  I really hope it works out under the loads
> we want to test. :)
> Like I said, anyone else feel free to correct me - I'm still
> just getting started with RHCS/GFS/etc. at this point.
> -Brenton Rothchild
> Omer Faruk Sen wrote:
> > Hi,
> >
> > I want to install a mysql cluster. But I want to ask which path do I have
> > to follow? Or there is any special precautions that I have to take care
> > before and after installing mysql and redhat cluster suite.
> >
> > My first impression is to install 2 node cluster it is better for me to
> > use GFS and a iscsi solution for a cheaper solution. But I have
> > understood from my readings that I can't setup an active-active mysql
> > cluster using redhat cluster + GFS. Because one node must be locked for
> > writing. Thus I think installing the second server for writing may be
> > just for
> > availability not for combining 2 machines power ( I mean using
> > active-acvtive).
> >
> > Then I think to install 2 machines for write (one is standby) on a redhat
> > cluster using GFS on a ISCSI system and adding a number of machines that
> > use the same GFS partition for msqyl read operations is what I have to
> > follow .. right?
> >
> > PS: By the way can you give me an URL that details mysql and redhat
> > cluster + gfs installation? Or is there any ?
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster

It is possible to use mysql on shared storage with enabled external locking 
and also disabling the query cache and few other things:

query_cache_size= 0
query_cache_type= 0
delay_key_write = OFF

in mysqld section

this configuration worked for my 10 node cluster .

When you finally buy enough memory, you will not have enough disk space. 
	-- Murphy's Computer Laws n°3

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