On Tue, Feb 23, 2010 at 12:33 AM, Michael Lee <mail.list.steel.men...@gmail.com> wrote: > (1) A cluster cannot be enlarge(add more node into cluster) if it > already used more than half capacity: > > If every node has data more than it’s half capacity , the admin may not > bootstrapping new node into cluster, > > because old nodes must strip data belong to new node through > anti-compaction, the process will create a large tmp SSTable > file (for streaming), which may large than free disk space ( of one node ).
That's right, in the worst case. On average, any node sending to a bootstrap node will only have to anti-compact half its data. We have https://issues.apache.org/jira/browse/CASSANDRA-579 open to allow streaming data w/o first writing it locally. > (1) Is cassandra designed to waste half of it’s capacity? Yes, although I might describe it as "cassandra requires up to half its capacity as temporary space for compaction and anticompaction." http://wiki.apache.org/cassandra/MemtableSSTable That's the price you pay for no random writes. > (2) How to use node has 12 1TB disk?? You should use a better filesystem than ext3. :) We use xfs at rackspace. -Jonathan
