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From zeeman <zee...@zeeman.de>
Subject Re: Oracle Cluster configuration questions
Date Tue, 27 Jul 2010 10:00:19 GMT
Hi!
Thanks for the first response.

>> My goal is to persist the whole repository in the Oracle Database
(except
>> the search index and the revision log ;-) ) to keep backup effors
>> minimal.
>> I think this is a valid approach as I expect only small text files to
be
>> placed in the repository (and no (large) binary files).
>> 
>> Another question aries about the cluster failover:
>> * What happens if one node goes down?
>> I expect on restart the failing node will "replicate" the missed
updates
>> from the repoistory. But as the "repository" itself is already in the
>> database tables what does really happen? Is only the search index
>> refreshed?
> 
> All the journal events that the failed node missed when it was down will
> be replayed when the failed node comes back. This will 
> 1) Cause (re-) indexing of any items that changed while offline updating

> the local lucene index
> 2) invaidate any items in the shared local items state cache so that 
they
> are refreshed from the DB when required.

Ok, this is nearly what I expected.
But what is is this "shared local items state cache"?
Is this the normal cache every JCR node has? I would expect this cache is
only filled if a item is queried for and it does not try to synchronize
the
complete repository in the (in-memory?) cache. 
 
And as I'm usuing OracleFileSystem and OraclePersistenenceManager the
shared folder (in fact a table) should be up-to-date as the not-failed
node
has done its changes to the journal and the shared folder (the shared
table).


>> Also what happens if the local revision log / complete workspace folder
>> is
>> deleted?
> 
> The instance will rebuild from the year dot using the journal.
> 
>> I would expect that (a) the complete repository is somewhat replicated
>> (see above) and (b) the search index is rebuild. According to the
>> repository size that might take some time but should work without user
>> interaction. Is that right?
> 
> Correct
> 
>> Though what is a recommended place for the local JCR "workspace folder"
>> as
>> it only contains the search index and the revision log?
> 
> and iirc some other things like config.
> 
>> Is
>> <JBOSS>/server/default/tmp a good approach?
> 
> I would not call it tmp, its permanent local state.

What is permanent on of local repository home? 
* The cache is in-memory (I guess), 
* the workspace configuration can be recreated from the repository.xml (as
on the very first start),
* the search index ca be rebuild and 
* the repository content is always up-to-date in the table. 

My overall goal is to minimize backup efforts and doing no backup of the
nodes' local repository folder would be very nice (as I hope it can be
rebuild in case of a failure).

Kind regards,
Sebastian


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