[Mulgara-general] Fedora user looking for a push in the right direction

[Paul Gearon]

Hi Michael,

Unfortunately, Mulgara uses locking to ensure that only one instance
at a time is ever accessing the storage files. This is done for the
ACID requirements on writing.

It's conceivable to come up with a read-only version of Mulgara that
could run concurrently if this is really needed. But it would need
significant work throughout the system if you wanted to allow a
read-only instance to change over to read-write were the original
read-write system to fall over.

Sorry I don't have a better answer for you.

Regards,
Paul Gearon

On Thu, May 20, 2010 at 3:51 PM, Michael Della Bitta
<michael_della_bitta at nypl.org> wrote:
> Hi, I'm indirectly a user of Mulgara by way of running Fedora Commons Server.
>
> I'm looking for information about running multiple instances of
> Mulgara concurrently over the same data, or implementing failover
> somehow. Basically we intend to run multiple Fedora instances over the
> same object store, while only allowing one instance of Fedora to
> actually perform writes. Is there a way to run multiple Mulgara
> instances this way as well? If not, is there a way to queue up
> instances to replace the sole active Mulgara instance, should it fail?
>
> I spent some time trolling the wiki but didn't come up with anything
> (save for stuff that was mentioned about XA2).
>
> Thanks for any help that anybody might be able to provide.
>
> Michael Della Bitta
> Senior Applications Developer
> Department of Strategy
> The New York Public Library
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