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From Jeremy Hanna <jeremy.hanna1...@gmail.com>
Subject Re: Forcing Cassandra to free up some space
Date Fri, 27 May 2011 03:43:41 GMT
For the purposes of clearing out disk space, you might also occasionally check to see if you
have snapshots that you no longer need.  Certain operations create snapshots (point-in-time
backups of sstables) in the (default) /var/lib/cassandra/data/<keyspace_name>/snapshots
directory.

If you are absolutely sure that you no longer need a particular snapshot of the sstables,
you can reclaim a decent amount of space that way.

I'm not sure of all of the other GC discussion going on but that's one way to reclaim some
space.

On May 26, 2011, at 1:09 PM, Konstantin Naryshkin wrote:

> I have a basic understanding of how Cassandra handles the file system (flushes in Memtables
out to SSTables, SSTables get compacted) and I understand that old files are only deleted
when a node is restarted, when Java does a GC, or when Cassandra feels like it is running
out of space.
> 
> My question is, is there some way for us to hurry the process along? We have a data that
we do a lot of inserts into and then delete the data several hours later. We would like it
if we could free up disk space (since our disks, though large, are shared with other applications).
So far, the action sequence to accomplish this is:
> nodetoo flush -> nodetool repair -> nodetool compact -> ??
> 
> Is there a way for me to make (or even gently suggest to) Cassandra that it may be a
good time to free up some space?


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