in the Cassandra wiki, I found this "
ColumnFamilyStoreMBean exposes sstable space used as getLiveDiskSpaceUsed (only includes size of non-obsolete files) and getTotalDiskSpaceUsed (includes everything)."
maybe this is the answer.

On Wed, Dec 7, 2011 at 11:57 AM, 祝海通 <> wrote:

We are using Cassandra 1.0.2. I am testing the TTL with loading 400G.  
When all the data are expired, I waited for some hours. 
Later, the nodetool ring is still have 90GB. So I made a major compaction. 
Then there are 30GB from the nodetool ring. After I saw the file system,I found there are zero sstable.
I don't know where comes the 30GB?

Best Regards