title: RocksDB in Kafka stream reporting no space when there is space available
body: <p>I have a Streams application with a <code>GlobalKtable</code> backed by RocksDB that’s failing. I was originally getting the error described in <a href="https://issues.apache.org/jira/browse/KAFKA-6327" rel="nofollow noreferrer">https://issues.apache.org/jira/browse/KAFKA-6327</a>, so I upgraded RocksDB to v5.14.2, which now gives a more explicit error: <code>org.rocksdb.RocksDBException: While open a file for appending: /kafka_streams/...snip.../000295.sst: No space left on device</code></p>
  
  <p>The directory in which the RocksDB spills to disk (a file mount on RHEL) seems to have ample space (<code>Size: 5.4G  Used: 2.8G  Available: 2.6G  Use%: 52%</code>). I'm assuming that it's actually trying to allocate more than the remaining 2.6G, but that seems unlikely; there isn't that much data in the topic. </p>
  
  <p>I found details on configuring RocksDB away from the defaults at <a href="https://docs.confluent.io/current/streams/developer-guide/config-streams.html#rocksdb-config-setter" rel="nofollow noreferrer">https://docs.confluent.io/current/streams/developer-guide/config-streams.html#rocksdb-config-setter</a>, but I don't see anything obvious that could potentially resolve the issue.</p>
  
  <p>I haven't found any bug reports related to an issue like this, and I'm at a loss for troubleshooting next steps.</p>
  
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  <p>Edited to add:
  I just ran the streams application on my local development machine against the same Kafka environment having the problem above. While the state stores were being loaded, the state store directory drifted up to a high of 3.1G and then settled at around 2.1G. It never got close to the 5G available on our development server. I haven't gotten any closer to finding an answer.</p>