What is system.size_estimates in cassandra and plausible reasons behind high disk consumption

Question

I've been using cassandra on two nodes where one of them ran out of disk space and went down. When I checked, I've observed the size of size_estimates to be ~30GB.

I've removed sstable files from my data directories and restarted the node. Was curious about the root cause of the problem.

Answer 1

As the name suggests, the size_estimates contains estimates of partition counts and their corresponding size. The estimates are calculated and recorded in the background every 5 minutes.

You haven't provided enough information in your post to determine why the node ran out of space. You'll need to analyse the logs for clues. Cheers!