Automatic reset of index

Hi Guys,

I have a single node elasticsearch instance ( 0.90 version) running on a single machine ( 8GB RAM, dual core CPU) having RHEL 5.6

After having indexed close to 2 million documents, it runs fine for a few hours and then restarts on its own, wiping out the index in the process. I now need to reindex all the documents again.

Here are the modifications i made to the default elasticsearch.yml file :

index.number_of_shards: 5
index.cache.field.type: soft
index.fielddata.cache: soft
index.cache.field.expire: 5m
indices.fielddata.cache.size: 10%
indices.fielddata.cache.expire : 5m
index.store.type: mmapfs
bootstrap.mlockall: true
discovery.zen.ping.multicast.enabled: false
action.disable_delete_all_indices: true
script.disable_dynamic: true

I use the elasticsearch service wrapper to start and stop the instance. In the elasticsearch.conf file, i have set the heap size to 2GB :

set.default.ES_HEAP_SIZE=2048

Any help is diagnosing the problem will be appreciated.
Thanks guys!