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From "Wei Deng (JIRA)" <>
Subject [jira] [Created] (CASSANDRA-6958) upgradesstables does not maintain levels for existing SSTables
Date Mon, 31 Mar 2014 13:52:16 GMT
Wei Deng created CASSANDRA-6958:

             Summary: upgradesstables does not maintain levels for existing SSTables
                 Key: CASSANDRA-6958
             Project: Cassandra
          Issue Type: Bug
          Components: Core
            Reporter: Wei Deng
            Priority: Critical

Initially ran into this issue on a DSE 3.2 (C* 1.2) to DSE 4.0 (C* 2.0) upgrade, and then
I was able to reproduce it when testing an upgrade from C* 2.0.5 to C* 2.1-beta so the problem
still exists in the latest code.

Basically after you've upgraded to the new version and run "nodetool upgradesstables" on a
CF/table that has been using LCS, then all of the non-L0 SSTables will be changed to L0 in
the upgraded SSTables. In other words, they don't maintain their level and will have to go
through the compaction again. The problem is that if you've got thousands of non-L0 SSTables
before the upgrade, then all of these files showing up in L0 will push the system to do STCS
and start to build some huge L0 tables. If a user doesn't budget enough free space (for example,
if they used the recommended guideline and only budgeted 10% of free space because LCS is
in use), then this STCS in L0 effect will have them run out of space.

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