Hi Ryan,
Hello. My company is currently looking to evaluate Sequoia as a mysql
clustering solution and I am wondering if anyone can share their
experiences with the software.
Very few people are willing to share their experience in using open
source Sequoia even though there are quite a bit of production users out
there. However I can tell you what I have seen so far (my opinion is
probably biased since I was the designer of Sequoia ;-)).
We may potentially be rolling out the service in our production
environment and would like to know of any glaring limitations of the
software if there are any. Also, can anyone point me to configuration
documents for getting the software up and running?
You can find the documentation at http://sequoia.continuent.org/Manuals
There is no fundamental difference between 2.x and 3.x but 3.x is now
deprecated and not supported (4.0 is in the works). Config file format
is slightly different.
Besides what the bug tracker can tell you, I would say Sequoia is a
solution that is more geared towards high availability than performance.
Depending on the parallelism you have in your workload you may see no or
little improvement in performance. Note that it is still the same
database that will in the end execute the query, so individual queries
won't execute faster, we just spread the load on multiple nodes. Writes
are replicated on all nodes, so you will never see improvement on write
speed performance.
Sequoia has all the required management mechanics but it does not
provide automated management, you will have to write your own scripts
for that. Continuent provides a commercial product based on Sequoia that
will handle that nicely. If you prefer staying the open source route,
you can seek for help on the mailing list or get help from consultants
(I do consulting ;-)).
How well does the software work with PHP? Most of our backend systems
are tomcat 5.5/6.x but we still maintain legacy PHP software where
needed.
The software was originally designed to work with Java but the Myosotis
project adds direct MySQL protocol support so that you can run with
legacy PHP applications. Just be aware that you won't have transparent
failover with Myosotis. Another option is to use ODBSequoia, an ODBC
implementation if you PHP application uses a db library that can take an
ODBC driver.
Sequoia is highly configurable which sometimes confuses users and can
lead to poor design or integration. We are trying to simplify
configuration for Sequoia 4 but there will still be application specific
optimizations or architectures that cannot be automatically guessed. One
thing to keep in mind is that Sequoia provides synchronous
statement-based replication and the strong consistency provided does not
support network partitions. Therefore, you have to think twice if you
want to use it in a WAN environment.
If some of the things I mentioned are not clear to you or don't ring a
bell, you can read this article that should give you an overview of the
problems you are going to face depending on what solution you go for
(Sequoia or not): http://infoscience.epfl.ch/record/118488
Thanks for your interest in Sequoia,
Emmanuel
--
Emmanuel Cecchet - Research scientist
EPFL - LABOS/DSLAB - IN.N 317
Phone: +41-21-693-7558
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