Emmanuel Cecchet wrote:
Alex wrote:
However, then it seems that using some sort of RAID is expected,
because controller startup results in:
14:28:00,868 ERROR controller.xml.DatabasesParser SingleDB
configuration cannot be used in a distributed virtual database.
14:28:00,871 ERROR controller.xml.DatabasesParser Failed to create
the request manager.
org.xml.sax.SAXException: SingleDB configuration cannot be used in a
distributed virtual database.
You are absolutely right !
The options in my virtualdatabase file regarding SingleDB are:
<RequestScheduler>
<SingleDBScheduler level="passThrough" />
</RequestScheduler>
<LoadBalancer>
<SingleDB/> <!-- no children allowed! -->
</LoadBalancer>
As far as I can see, this is correct - I do want just a single
backend behind both controllers.
The key is getting the two controllers talking to each other (hence
me adding <Distribution> tag)...
So if you have 1 backend behind each controller that means that you
have 2 backends total, which is no more Single ;-)
Ok I know the wording is confusing but once I wrote somewhere the
historic reasons for that.
So anyway, the baseline is that you need to use a RAIDb-1
configuration if you have multiple controllers, even if only 1 backend
is attached to each of them.
Ahh, yes, this is starting to make sense.
I've just been trying it as a Raidb-1 setup and I'm definitely getting
further now, so thanks for that!
Maybe I'm barking up the wrong tree here somehow.
The desired outcome for this setup is two machines, neither of which
is a single point of failure, hence wanting each machine having a
controller with a single backend behind it...
RAIDb-1 is what you are looking for ! :-)
Good stuff!
I think I'm almost there. I'm getting "not last man down" problem now
(see other msg for details).
Alex
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