Hi,

i have a question related to the index-process of hibernate search.
Is it possible to let multiple servers write updates to the index file.
The setup i mean:
4 linux vm with one tomcat server on every vm. The vms share a network drive and one database on another linux vm.
So instead of setting up a JMS-Environment, is it possible to let every server write its changes to same shared index?

Hi,
no that's not possible, by the design of Lucene only one VM can write at the index at the same time; that's why we propose the queue based architecture.

Generally, you can't even share a Lucene index on a shared disk: performance will be worse and you'll face many issues with locking.

To cluster the index, you either have to use the master/slave directory providers which will periodically sync remote directories, or use the clustered index via Infinispan to provide quick realtime updates to each node.

thx for the fast reply.
JMS or Infinispan. I havent done any of those.
Which one is lighter and faster to get to run?

actually it's not about either Infinispan or JMS:
- Infinispan is a place to store the index (to share it properly)
- a queue is used to make sure only one node writes to the shared index

The queue can be either JMS or JGroups; JGroups might be a bit simpler to setup but JMS provides a persistent queue (if the master server crashes unprocessed messages are not lost).
JMS is very simple to setup in an application server, Tomcat doesn't have one so you'll have to pick one and use it embedded from your application - sorry I can't help you with that.

Infinispan is an alternative to the shared filesystems used by the backends in Search which copy the files (at file system level), you might need that only if you require changes to be visible to each node very quickly (realtime).

I'd suggest you to read the book, the JMS architecture is explained in depth there (though Infinispan didn't exist at the time of writing).

Thx for all the Help!
I´ll try to go the way with JMS and the shared FS.
Its actually a very good idea to get the Book :) i´ll do that.
I will report my success or fail later. (And how long it really took)