Added to http://wiki.apache.org/cassandra/MemtableSSTable:
SSTables that are obsoleted by a compaction are deleted asynchronously when the JVM performs a GC. You can force a GC from jconsole if necessary but this is not necessary; Cassandra will force one itself if it detects that it is low on space. A compaction marker is also added to obsolete sstables so they can be deleted on startup if the server does not perform a GC before being restarted. CFStoreMBean exposes sstable space used as getLiveDiskSpaceUsed (only includes size of non-obsolete files) and getLiveDiskSpaceUsed (includes everything). On Tue, Apr 20, 2010 at 12:33 PM, B. Todd Burruss <bburr...@real.com> wrote: > i'm trying to draw some correlation between the size of my data and the > space used on disk. i have set <GCGraceSeconds>1</GCGraceSeconds> so there > isn't any reason to keep data around. > > my approach is this: > > after only doing "puts" to cassandra for a while i stop my client and want > to perform the proper "cleanup" and/or "compact" operations that will reduce > the disk space used to a minimum. however i can't seem to figure it out. > i've done "major compaction", "cleanup", etc. but doesn't seem to get the > job done > > so two questions > > - what procedure is suggested to get rid of all unnecessary data? > - and what does the following "Compacted" file mean? seams like it is > marking "88" as compacted, but there are no more compactions happening > according to compaction mgr > > -rw-rw-r-- 1 bburruss bburruss 0 Apr 20 08:32 bucket-88-Compacted > -rw-rw-r-- 1 bburruss bburruss 1445218042 Apr 19 21:39 bucket-88-Data.db > -rw-rw-r-- 1 bburruss bburruss 12255925 Apr 19 21:39 bucket-88-Filter.db > -rw-rw-r-- 1 bburruss bburruss 451806386 Apr 19 21:39 bucket-88-Index.db > >
