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Posted to commits@cassandra.apache.org by "Elliott Sims (JIRA)" <ji...@apache.org> on 2018/07/24 19:13:00 UTC

[jira] [Created] (CASSANDRA-14587) TrueDiskSpaceUsed overcounts snapshots

Elliott Sims created CASSANDRA-14587:
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             Summary: TrueDiskSpaceUsed overcounts snapshots
                 Key: CASSANDRA-14587
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14587
             Project: Cassandra
          Issue Type: Bug
          Components: Tools
         Environment: Debian 8

Cassandra 3.11.2
            Reporter: Elliott Sims


Running 'nodetool listsnapshots' seems to overcount "TrueDiskSpaceUsed" under some circumstances.  Specifically when there's a large number of snapshots.  I suspect that it's not deduplicating space used when multiple snapshots share sstables that are not part of the current table.

Results of "nodetool listsnapshots":
Total TrueDiskSpaceUsed: 396.11 MiB
Results of "du -hcs" on the table's directory:
18M    total

This is 50+ snapshots (every minute) run with "-t <datestamp> -sf --column-family <tablename> <keyspace>"
The results of a "du -hcs -L <directory" come out pretty close to the "TrueDiskSpaceUsed"

I have only tested against 3.11.2, but have no reason to believe it's unique to that version or even 3.x.



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