- Pause indexing
- Issue a flush request
- Rsync data directories somewhere
- Resume indexing
This is technically a very naive approach, since a simple rsync of the data dirs will include replicas too. If you were more diligent you could check the state files in each shard directory and only copy out the primaries.
You can just google "elasticsearch rsync" to get information, and even scripts, that will do this for you. The thing is... you REALLY need to know what you're doing when you go this route.
Also, you can try the gateway feature. Gateway is actually pretty straightforward. Restore WILL be slow though. And for many scenarios ... it is not ideal. (You don't want to take a day, or even a few, to restore after a failure.)
I think the best advice is...
Update to 1.0.
Just go to 1.0 and do snapshots... you will save yourself A LOT of headaches.