try nodetool drain. It will flush everything to disk and the commit log will be truncated.

HH can be ignored. If you really want them gone they can be purged using the JMX interface, or you can stop the node and delete the sstables. 


Cheers
 
-----------------
Aaron Morton
Freelance Cassandra Developer
New Zealand

@aaronmorton

On 13/12/2012, at 10:35 AM, Sergey Olefir <solf.lists@gmail.com> wrote:

Nick Bailey-2 wrote
Dropping a keyspace causes a snapshot to be taken of the keyspace before
it
is removed from the schema. So it won't actually delete any data. You can
manually delete the data from /var/lib/cassandra/
<ks>
/&lt;cf[s]&gt;/snapshots

Indeed, it looks like snapshot is on the file system. However it looks like
it is not the only thing by a long shot, i.e.:
cassa1-1:/var/log/cassandra# du -k /spool1/cassandra/data/1.1/
375372
/spool1/cassandra/data/1.1/rainmanLoadTestKeyspace/marquisColumnFamily/snapshots/1355222054452-marquisColumnFamily
375376
/spool1/cassandra/data/1.1/rainmanLoadTestKeyspace/marquisColumnFamily/snapshots
375380
/spool1/cassandra/data/1.1/rainmanLoadTestKeyspace/marquisColumnFamily
375384  /spool1/cassandra/data/1.1/rainmanLoadTestKeyspace
4       /spool1/cassandra/data/1.1/system/Versions
52      /spool1/cassandra/data/1.1/system/schema_columns
4       /spool1/cassandra/data/1.1/system/Schema
28      /spool1/cassandra/data/1.1/system/NodeIdInfo
4       /spool1/cassandra/data/1.1/system/Migrations
28      /spool1/cassandra/data/1.1/system/schema_keyspaces
28      /spool1/cassandra/data/1.1/system/schema_columnfamilies
786348  /spool1/cassandra/data/1.1/system/HintsColumnFamily
52      /spool1/cassandra/data/1.1/system/LocationInfo
4       /spool1/cassandra/data/1.1/system/IndexInfo
786556  /spool1/cassandra/data/1.1/system
1161944 /spool1/cassandra/data/1.1/


And also 700+MB in the commitlog. Neither of which seemed to 'go away' on
its own when idle or even after running nodetool repair/cleanup and even
dropping keyspace.

I suppose these hints and commitlog may be the reason behind huge difference
in load on nodes -- but why does it happen and more importantly is it
harmful? Will it keep accumulating?



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