Moreover, if you are using SSDs keeping data directories and commitlog on separate disks wont provide much benefit.
As Nate said, relying on RAID with RF=1 is not good design. Cassandra replicas provide greater fault tolerance and HA as they are on different nodes. Thanks Anuj Sent from Yahoo Mail on Android From:"Nate McCall" <n...@thelastpickle.com> Date:Sun, 19 Jul, 2015 at 1:20 am Subject:Re: Unbalanced disk load > > I am currently benchmarking Cassandra with three machines, and on each > machine I am seeing an unbalanced distribution of data among the data > directories (1 per disk). > I am concerned that this affects my write performance, is there anything that > I can make the distribution be more even? Would raid0 be my best option? > Using LeveledCompactionStrategy should provide a much better balance. However, depending on your use case, this may not be the right choice for your workload, in which case RAID0 with a single data_dir will be the best option. > Total size of data is about 2TB, 14B records, all unique. Replication factor >of 1. RF=1 means *no* redundancy which is a bad idea to run in production (and sort of defeats the purpose of a system like Cassandra). This is not going to be an accurate a picture for a load test as it eliminates a lot of cross-node traffic which you would see with a higher Replication Factor. -- ----------------- Nate McCall Austin, TX @zznate Co-Founder & Sr. Technical Consultant Apache Cassandra Consulting http://www.thelastpickle.com
