Hi Jonathan, Good to know. We will certainly upgrade to 0.7.8.
Also, here is the link to that post I came across earlier: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Files-not-deleted-after-compaction-and-GCed-td5960453.html best, -- Y. On Tue, Aug 2, 2011 at 5:36 PM, Jonathan Ellis <jbel...@gmail.com> wrote: > I don't remember a removing-compacted-files bug in 0.7.0, but you > should absolutely upgrade to 0.7.8 for several dozen other fixes, > including some severe ones -- see NEWS.txt. > > On Tue, Aug 2, 2011 at 4:29 PM, Yiming Sun <yiming....@gmail.com> wrote: > > Hi Jeremiah, > > > > Thank you for the information - it certainly is a relief. Two questions > > though: > > > > 1. I came across an old thread which seemed to be saying 0.7.0 cassandra > has > > a bug and doesn't remove these compact files properly. Should we upgrade > to > > a newer version that has this bug fixed? > > > > 2. Do we must do the garbage collection via Jconsole manually? Is there > > anyway I can force the GC in our code? (we are using Hector as our java > > client). > > > > Thanks! > > > > > > > > On Tue, Aug 2, 2011 at 5:19 PM, Jeremiah Jordan > > <jeremiah.jor...@morningstar.com> wrote: > >> > >> Connect with jconsole and run garbage collection. > >> All of the files that have a -Compacted with the same name will get > >> deleted the next time a full garbage collection runs, or when the node > >> is restarted. They have already been combined into new files, the old > >> ones just haven't been deleted yet. > >> > >> On Tue, 2011-08-02 at 16:09 -0400, Yiming Sun wrote: > >> > Hi, > >> > > >> > I am new to Cassandra, and am hoping someone could help me understand > >> > the (large amount of small) data files on disk that Cassandra > >> > generates. > >> > > >> > The reason we are using Cassandra is because we are dealing with > >> > thousands to millions of small text files on disk, so we are > >> > experimenting with Cassandra hoping that by dropping the files > >> > contents into Cassandra, it will achieve more efficient disk usage > >> > because Cassandra is going to aggregate them into bigger files (one > >> > file per column family, according to the wiki). > >> > > >> > But after we pushed a subset of the files into a single node Cassandra > >> > v0.7.0 instance, we noted that in the Cassandra data directory for the > >> > keyspace, there are 8.5 million very small files, most are named > >> > > >> > <SuperColumnFamilyName>-e-<nnnnn>.Filter.db > >> > <SuperColumnFamilyName>-e-<nnnnn>.Compacted.db > >> > <SuperColumnFamilyName>-e-<nnnnn>.Index.db > >> > <SuperColumnFamilyName>-e-<nnnnn>.Statistics.db > >> > > >> > and among these files, the Compacted.db are always empty, Filter and > >> > Index are under 100 bytes, and Statistics are around 4k. > >> > > >> > What are these files? Why are there so many of them? We originally > >> > hope that Cassandra was going to solve our issue with the small files > >> > we have, but now it doesn't seem to help -- we still end up with tons > >> > of small files. Is there any way to reduce/combine these small > >> > files? > >> > > >> > Thanks. > >> > > >> > -- Y. > >> > > > > > > > > -- > Jonathan Ellis > Project Chair, Apache Cassandra > co-founder of DataStax, the source for professional Cassandra support > http://www.datastax.com >
