[Linux-cluster] FWD: Question on RH Cluster from a MySQL Customer

[Ivan Zoratti]

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 at mysql.com
   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 at mysql.com
>>   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