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I have a Streams application with a GlobalKtable backed by RocksDB that’s failing. I was originally getting the error described in https://issues.apache.org/jira/browse/KAFKA-6327, so I upgraded RocksDB to v5.14.2, which now gives a more explicit error: org.rocksdb.RocksDBException: While open a file for appending: /kafka_streams/...snip.../000295.sst: No space left on device

The directory in which the RocksDB spills to disk (a file mount on RHEL) seems to have ample space (Size: 5.4G Used: 2.8G Available: 2.6G Use%: 52%). 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.

I found details on configuring RocksDB away from the defaults at https://docs.confluent.io/current/streams/developer-guide/config-streams.html#rocksdb-config-setter, but I don't see anything obvious that could potentially resolve the issue.

I haven't found any bug reports related to an issue like this, and I'm at a loss for troubleshooting next steps.

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.

Ickster
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I never found an answer to why the disk usage in the deployed environment was behaving this way, but I eventually got more space allocated out of desperation; as the stream was processing, it consumed as much as 14GB of space before settling down around 3-4GB. I assume the disk space error was because RocksDB was trying to allocate space, not that it had written to it.

I've added a 'rule of thumb' that I should allocate 4x the disk space I expect for streaming applications.

Ickster
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