Emmanuel,
Fine, I'm convinced about the load balance at the driver's level, but I'm not yet sure about two other important features:
1) does the driver has any type o query cache or is it available only at the controller level ? If so, then even the cached queries result in network trafic,
2) can the driver manage different replication models (RAIDb0, RAID1...) ? As far as I an see, these models make sense only at the controller's level, right ?
In any case, I think we can bennefit from using our framework in the sense that it can automatically detect the available controllers on the network. This way, the URL:
jdbc:sequoia://controller1,controller2,controller3/myDB\?preferredController=controller1,controller2|
could be simplified to:
jdbc:sequoia://myDB|
Thanks again for your patience.
F. Lucchese
On Fri Apr 13 21:09 , Emmanuel Cecchet <[EMAIL PROTECTED]> sent:
> Do you see any obvious flaws into these ideas ?
>
Actually the Sequoia driver probably implements already all the features
you need.
If you look at the load balancing capabilities of the driver described
at
http://sequoia.continuent.org/doc/infocenter/topic/org.continuent.sequoia.doc/html/Balancing_client_connections_to_controllers.html,
something like:
|jdbc:sequoia://controller1,controller2,controller3/myDB\?preferredController=controller1,controller2|
will allow clients to first load balance on controller1 and controller2
(let's suppose they are local) and only switch to a remote controller3
if and only if controller1 and controller2 are down.
Sequoia drivers are also capable of transparent failover and can
seamlessly reconnect and pursue any in-flight transaction in case of a
controller failure. This way the application never see any failure
unless the entire system is unavailable.
Note that each controller maintains its own local copy of the recovery
log which allows to resynchronize with remote controllers.
Hope this clarifies things,
Emmanuel
--
Emmanuel Cecchet
Chief Scientific Officer, Continuent
Blog: http://emanux.blogspot.com/
Open source: http://www.continuent.org
Corporate: http://www.continuent.com
Skype: emmanuel_cecchet
Cell: +33 687 342 685
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