Hi Jon,
I'm new to the list and to sequoia, and so I'm trying to understand
and realize the capabilities of this product.
Welcome and thanks for your interest.
We are trying to find a database architecture as the backend for our
Java apps, with the only requisite of four nine availability (99,99).
The load will always be low. My view is from the infrastructure point
(I know that I should pass this problem to our dev part, I've done it
indeed...), and that's why I want to build a base platform for
deploying different client solutions in our virtualized datacenter: My
needs should be just two backend databases ("mirrored" ideally)
controlled by two controllers replicating everything.
If you need only 2 database backends, they can also be under the same
controller. The controller becomes a single point of failure but this
can be fine if it is co-located with the application and the application
is not clustered. Now if your application is also replicated, you can
have 2 controllers with 1 db each.
I was looking at Sequoia+Postgre as the platform, and have been
reading all the documentation it seems to fit well. I have some doubts:
1) Which should be my simplest configuration? RADIb-1 in each
controller would give me 4 backends... That is supposing that two
controllers cannot control the same two backends, is that allright?
RAIDb-1 is for mirroring so you are on the right path. You are right
that backends cannot be shared between controllers. But one controller
can have multiple backends. So I am not sure if you just need to
replicate 2 databases on different machines which will lead to 4
backends (2 for each controller as you mentioned) or just 1 database in
which case 1 backend per controller is enough.
2) I tried using simpleDB in each controller, but I got errors saying
that no distribution can be done with simpleDB... Is that allright?
SimpleDB is only meant for 1 database backend only (cluster-wide). If
you replicate a database, you have 2 backends in the cluster and you
need RAIDb-1.
3) In the configs I'm proposing, where should the RecoveryLogs be
stored? In the same backends (maybe only in one of the two?) that
compose the DBclusters?
I usually recommend to have the recovery log local to each controller.
Given the small workload that you will have, a Java database like Derby
or Hsqldb can do it on the controller.
Hosting the recovery log on a database backend is error prone for
administration and when you need to service the database node you will
have to stop your controller that will not be able to work without its
recovery log.
I hope this helps,
Emmanuel
--
Emmanuel Cecchet
FTO @ Frog Thinker
Open Source Development & Consulting
--
Web: http://www.frogthinker.org
email: [EMAIL PROTECTED]
Skype: emmanuel_cecchet
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