We utilize Elasticsearch primarily for Logstash data and with the recent upgrade to 2.0 we saw about a 2.5X disk space increase. Same data, same data types and fields.
logstash-2015.11.10 - 179.3m - 139.6GB
logstash-2015.11.16 - 174.3m - 411.5GB
Not so much a question but this is likely due to the Doc Values turned on for all non-analyzed fields by default where as before we were only use Doc Values for the @timestamp field.