问题
we are running test cassandra cluster of 8 nodes running in single DC using Simple snitch and DateTieredCompactionStrategy Cassandra Version 2.1.3 after adding new node(9th) to the cluster we see that number of sstables on newly joined server roughly equals to sum of all sstables on all servers in the cluster. and that number is huge as tens of thousands of sstables on newly added server.
Q1:is that what we should expect to happen?
Furthermore newly added server seems isn't overloaded, basically there are no pending/scheduled compactions but the number of sstables isn't decreasing.
Q2:what could be the reason of not reducing number of sstables?
Q3:what we need to do to reduce number of sstables per server?
Thanks for your help
回答1:
This is known (unexpected, but not unsurprising) behavior due to the design of DTCS. It will happen, every time, if max_sstable_age_days is below the ttl cutoff. It will also happen when you remove a node from the cluster.
I'm planning on discussing this at C* Summit 2015 if my talk is accepted, and I've proposed an alternative approach to DTCS in https://issues.apache.org/jira/browse/CASSANDRA-9666
来源：https://stackoverflow.com/questions/29431217/huge-number-of-sstables-after-adding-server-to-existing-cluster