Hi all,
The cluster has been configured correctly with this basic settings:
- Two systems (W2003) with 2 postgre 8.3 (one each), 2 HSQLDB 1.8 for
the RecoveryLogs (one each) and 2 sequoia controllers (one each)
clustering with JGroups
- Sequoia won't be loaded at boot, since as is a cluster, you don't now
why did the machine boot (failure, maintenance, ...), so it has no
sense. Is this ok?
I have two questions regarding the "jump" to production systems:
- For the periodic manteinance of the cluster backups, how could some
console commands (backup a backend, purge RLog1, transfer and purge
RLog2) be put in a batch job (W2003)?
- How could the two sequoias be monitored and health checked from the
"network"? Just checking the ports shouldn't be enough...
Thanx in advance!
Jon
Jon Urionaguena escribió:
Thanx Emmanuel,
I will keep you informed.. ;-)
Emmanuel Cecchet escribió:
Hi
Jon,
Then in the config, I should use a RAIDb-1
config in each controller specifying just one backend in each (so, not
doing mirroring inside de RAIDb...)? I cannot specify the two same
backends to the two controllers, can I?
You are correct, just 1 backend in each controller. You cannot share
backends between controllers.
Keep us posted with your progress,
Emmanuel
Emmanuel Cecchet escribió:
Jon,
I maybe didn't explain correctly my
problematic issues... What we need is the simplest arch to hold a
database system with no single point of failure, but this database
(composed by two backends in the simplest form) should look as only one
to our apps. So what I think is that we MUST use two controllers, and I
was looking for the correct implementation. As I see, two controllers
could use a singleDB each (I could not start this config... I will
review this case if it's the correct for us...). Is that ok?
No, SingleDB can only be used with one controller without replication.
If you need replication, you have to use RAIDb-1 with a
<Distribution> element in the virtual database configuration file
so that the controllers are synchronized. Each controller can have a
single database backend but the virtual database will have a total of 2
replicated backends that will appear as a single database to the client
application.
Then the question should be, if these
two
database backends, each controlled by a different controller, are
indeed replicated (we can recover one from the other in case of
failure), the database system is fault tolerant with no single point of
failure, and functionally perfom as a single database to the
application... Is this Ok?
Yes, it is. You can look at the distributed RAIDb-1 demo that ships
with Sequoia. You can change the config to have a single backend per
controller and that should be similar to what you need to build.
I will use another small database in
each
controller for the RecoveryLog...
Thanks for your interest in Sequoia,
Emmanuel
Emmanuel Cecchet escribió:
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
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Jon Urionaguena Mendizabal <[EMAIL PROTECTED]>
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Jon Urionaguena Mendizabal <[EMAIL PROTECTED]>
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Jon Urionaguena Mendizabal <[EMAIL PROTECTED]>
Director de Proyectos www.nesys-st.com
Tfno: 94 406 0546 Móvil: 675 610 399
GPG: 01D3 27A9 A663 C89E 3F72 2C5B 4913 E546 C4AA 2A97
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