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From Julie <>
Subject Re: Cassandra disk space utilization WAY higher than I would expect
Date Thu, 08 Jul 2010 13:32:35 GMT
Jonathan Ellis <jbellis <at>> writes:

> "SSTables that are obsoleted by a compaction are deleted
> asynchronously when the JVM performs a GC. You can force a GC from
> jconsole if necessary, but Cassandra will force one itself if it
> detects that it is low on space. A compaction marker is also added to
> obsolete sstables so they can be deleted on startup if the server does
> not perform a GC before being restarted.
> "CFStoreMBean exposes sstable space used as getLiveDiskSpaceUsed (only
> includes size of non-obsolete files) and getTotalDiskSpaceUsed
> (includes everything)."

Thank you so much for your help.
If I'm reading this right, it sounds like the extra 76 GB of disk space being
used could be due to SSTables that are obsolete due to compaction but not yet
deleted.  But would I be able to see a big difference in cfstats then between
Space used (live) and Space used (total)?  Here's what is being reported for
this node:
		Space used (live): 113946099884
		Space used (total): 113946099884

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