Hi Robert,
This is great news, thanks a lot. You (and Wendy in another email)
have answered my questions, now I will start digging into more
details through the documentation.
Should you need any information regarding MySQL, I would be glad to
help.
Thanks again,
Kind Regards,
Ivan
--
Ivan Zoratti - Sales Engineering Manager EMEA
MySQL AB - Windsor - UK
Mobile: +44 7866 363 180
ivan@xxxxxxxxx
http://www.mysql.com
--
On 9 Mar 2007, at 15:41, Robert Peterson wrote:
Hi Ivan,
Answers embedded below:
Ivan Zoratti wrote:
Hi Robert,
First of all, thanks for your time, I really appreciate it.
I'd like to reply to two separate topics here: first, the
objective of my question and second, the cluster-awareness of
MySQL and the use of GFS with MySQL.
My original question was mainly related to the use of Piranha to
switch over a service (ie, a specific mysql daemon) from one
server to another, in case of fault. There should be only one
active service in the cluster, therefore no concurrency or locking
issues should happen.
The ideal system should be able to:
- have a list of services to launch on the cluster
- identify the node in the cluster suitable to host the service
(for example the node with less workload)
- check the availability of the service
- stop the service on a node (if the service is not already down)
and start the service on another node in case of fault
Fault tolerance in this case will be provided by the ability to
switch the service from one server to another in the cluster.
Scalability is not provided within the service, ie the limitation
in resources for the service consist of the resources available on
that specific server.
I understand that your cluster suite can provide this
functionality. I am mainly looking for a supported set of features
for an enterprise organisation.
Red Hat's Cluster Suite does all of this with the rgmanager service
(not piranha). I guess I'm not sure what you're asking here. Are you
asking what features rgmanager has? Its features are probably
documented
somewhere, but I don't know where offhand. I know it's quite
full-featured and allows you to do exactly what you listed:
provide High Availability (HA) of multiple services, stopping and
starting services throughout cluster, with different kinds of
dependencies. The Cluster FAQ has information on rgmanager here
that you may find helpful:
http://sources.redhat.com/cluster/faq.html#rgm_what
If you have questions that aren't covered by the FAQ, let me know
and I'll do my best to answer your questions.
The second topic is related to the use of MySQL with clusters and
specifically with GFS. It is what we use to call MySQL in active-
active clustering. I am afraid your documentation is not totally
accurate. Unfortunately, information on the Internet (and also on
our web site) are often contradictory.
It is indeed possible to run multiple mysqld services on different
cluster nodes, all sharing the same data structure on shared
storage, with this configuration:
- Only the MyISAM storage engine can be used
- Each mysqld service must start with the external-locking
parameter on
- Each mysqld service hase to have the query cache parameter off
(other cache mechanisms remain on, since they are automatically
invalidated by external locking)
Thanks for providing this information. I'll get it into the
cluster FAQ.
Maybe some day I'll find the time to play with this myself.
I am afraid this configuration still does not compete against
Oracle RAC. MySQL does not provide a solution that can be compared
1:1 with RAC. You may find some MySQL implementations much more
effective than RAC for certain environments, as you will certainly
find RAC performing better than MySQL on other implementations.
Based on the experience of the sales engineering team, customers
have never been disappointed by the technology that MySQL can
provide as an alternative to RAC. Decisions are based on many
other factors, such as the introduction of another (or a
different) database, the cost of migrating current applications
and compatibility with third party products. You can imagine we
are working hard to remove these obstacles.
Thanks again for your help,
Kind Regards,
Ivan
--
Ivan Zoratti - Sales Engineering Manager EMEA
MySQL AB - Windsor - UK
Mobile: +44 7866 363 180
ivan@xxxxxxxxx
http://www.mysql.com
If you have other questions, please let me know. You can either
email me directly or join the linux-cluster mailing list where you
can talk to people are using these features and everyone can
benefit from the discussion.
Regards,
Bob Peterson
Red Hat Cluster Suite
--
Linux-cluster mailing list
Linux-cluster@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/linux-cluster
