Hello Aaron, Thank you for getting back to me.
I will change to m1.large first to see how long it will take Cassandra node to die (if at all). If again not happy I will try more memory. I just want to test it step by step and see what the differences are. I will also change the cassandra-env file back to defaults. Is there an absolute minimum requirement for Cassandra in terms of memory? I might be wrong, but from my understanding we shouldn't have any problems given the amount of data we store per day (currently approximately 2-2.5G / day). Thank you in advance, Bill On Wed, Apr 11, 2012 at 7:33 PM, aaron morton <aa...@thelastpickle.com>wrote: > 'system_memory_in_mb' (3760) and the 'system_cpu_cores' (1) according to > our nodes' specification. We also changed the 'MAX_HEAP_SIZE' to 2G and the > 'HEAP_NEWSIZE' to 200M (we think the second is related to the Garbage > Collection). > > It's best to leave the default settings unless you know what you are doing > here. > > In case you find this useful, swap is off and unevictable memory seems to > be very high on all 3 servers (2.3GB, we usually observe the amount of > unevictable memory on other Linux servers of around 0-16KB) > > Cassandra locks the java memory so it cannot be swapped out. > > The problem is that the node we hit from our thrift interface dies > regularly (approximately after we store 2-2.5G of data). Error message: > OutOfMemoryError: Java Heap Space and according to the log it in fact used > all of the allocated memory. > > The easiest solution will be to use a larger EC2 instance. > > People normally use an m1.xlarge with 16Gb of ram (you would also try an > m1.large). > > If you are still experimenting I would suggest using the larger instances > so you can make some progress. Once you have a feel for how things work you > can then try to match the instances to your budget. > > Hope that helps. > > ----------------- > Aaron Morton > Freelance Developer > @aaronmorton > http://www.thelastpickle.com > > On 11/04/2012, at 1:54 AM, Vasileios Vlachos wrote: > > Hello, > > We are experimenting a bit with Cassandra lately (version 1.0.7) and we > seem to have some problems with memory. We use EC2 as our test environment > and we have three nodes with 3.7G of memory and 1 core @ 2.4G, all running > Ubuntu server 11.10. > > The problem is that the node we hit from our thrift interface dies > regularly (approximately after we store 2-2.5G of data). Error message: > OutOfMemoryError: Java Heap Space and according to the log it in fact used > all of the allocated memory. > > The nodes are under relatively constant load and store about 2000-4000 row > keys a minute, which are batched through the Trift interface in 10-30 row > keys at once (with about 50 columns each). The number of reads is very low > with around 1000-2000 a day and only requesting the data of a single row > key. The is currently only one used column family. > > The initial thought was that something was wrong in the cassandra-env.sh > file. So, we specified the variables 'system_memory_in_mb' (3760) and the > 'system_cpu_cores' (1) according to our nodes' specification. We also > changed the 'MAX_HEAP_SIZE' to 2G and the 'HEAP_NEWSIZE' to 200M (we think > the second is related to the Garbage Collection). Unfortunately, that did > not solve the issue and the node we hit via thrift keeps on dying regularly. > > In case you find this useful, swap is off and unevictable memory seems to > be very high on all 3 servers (2.3GB, we usually observe the amount of > unevictable memory on other Linux servers of around 0-16KB) (We are not > quite sure how the unevictable memory ties into Cassandra, its just > something we observed while looking into the problem). The CPU is pretty > much idle the entire time. The heap memory is clearly being reduced once in > a while according to nodetool, but obviously grows over the limit as time > goes by. > > Any ideas? Thanks in advance. > > Bill > > >
