Clustering Configuration Clarification

["craig.schaefer" <cr...@prodyna.com>]

Hello JR-Dev

I'm seeking a clarification to the Jackrabbit Wiki page on Clustering.
Specifically DataStore usage. There appears to be conflicting statements.

In the "Overview" section the page states :
"any DataStore (file or DB) is clusterable by its very nature, as they store
content by unique hash ids"

This leads me to conclude that the DataStore is allowed to be deployed as
either FileDataStore OR DbDataStore. The restriction is that the DB or FS
must be globally accessible to all Jackrabbit nodes.  I would conclude then
that hosting the common FileDataStore on NFS is acceptable.

However in the section "Persistence Manager Configuration" it states:

"The file system blob store does not support clustering, because it uses a
local directory. "

after talking about how a PM uses either internal or external (aka
DataStore) storage for BLOBs.

I assume the statement is more like:
"The file system blob store (FileDataStore) ONLY supports clustering when
hosted on an NFS".

Thanks,

Craig
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Re: Clustering Configuration Clarification

[Alexander Klimetschek <ak...@day.com>]

On Fri, Feb 12, 2010 at 09:57, craig.schaefer
<cr...@prodyna.com> wrote:
> However in the section "Persistence Manager Configuration" it states:
>
> "The file system blob store does not support clustering, because it uses a
> local directory. "
>
> after talking about how a PM uses either internal or external (aka
> DataStore) storage for BLOBs.
>
> I assume the statement is more like:
> "The file system blob store (FileDataStore) ONLY supports clustering when
> hosted on an NFS".

No, I think this is right. The persistence manager blob store is not
the same as the datastore and it does not use it at all. Blob store
simply means the persistence manager stores binaries in its local
directory (and not in the db, for example). It was an older
optimization that is now supposed to be replaced by the better
DataStore. Because of the local nature, the pm blob store is not
cluster-aware, whereas a DataStore is. Internally DataStore is handled
on a "higher" level, the PM blob store is an internal feature of some
PMs.

Regards,
Alex

-- 
Alexander Klimetschek
alexander.klimetschek@day.com