Database Reference
In-Depth Information
MemTable Sizes Are Too Large for the JVM Heap
Cassandra generally puts
n
+ 2 MemTables into resident memory where
n
is the
number of ColumnFamilys in the keyspace. Add another 1GB on top of that for
Cassandra to determine the best total heap size. However, going much beyond
8GB for the heap is not generally a good idea to begin with. The more memory
used in the heap, the longer the GC pause will be. A GC pause means that nearly
everything else in the system is put on hold until the garbage collection has com-
pleted.
Ring View Differs between Nodes
When the ring view differs between nodes, it is never a good thing. There is also
no easy way to recover from this state. The only way to recover is to do a full
cluster restart. A rolling restart won't work because the Gossip protocol from the
bad nodes will inform the newly booting good nodes of the bad state. A full cluster
restart and bringing the good nodes up first should enable the cluster to come back
up in a good state.
Insufficient User Resources
Any insufficient resource errors that appear in the logs may not initially appear to
be caused by insufficient resources. In other words, the errors are not as explicit as
just saying the resources are insufficient. Here are some of the log lines that you
may see and their associated error type:
Insufficient as (address space) or
memlock
setting:
ERROR [SSTableBatchOpen:1] 2012-07-25
15:46:02,913
AbstractCassandraDaemon.java (line 139) Fatal
exception in
thread Thread[SSTableBatchOpen:1,5,main]
java.io.IOError: java.
io.IOException: Map failed at . . .
Insufficient
memlock
settings:
