> I would like to understand how we can capture network latencies between a > 1GbE and 10GbE for ex. Cassandra reports two latencies.
The CF latencies reported by nodetool cfstats, nodetool cfhistograms and the CF MBeans cover the local time it takes to read or write the data. This does not include any local wait times, network latency or coordinator overhead. The Storage Proxy latency from nodetool proxyhistograms and the StorageProxy MBean is the total latency for a request on a coordinator. Under load, with a consistent workload, the CF latency should not vary too much. While the request latency can increase as wait time becomes more of an factor. Additionally streaming is throttled which you may want to increase, see the the yaml file. > We will soon be adding SSD's and was wondering how Cassandra can utilize the > 10GbE and the SSD's and if there are specific tuning that is required. You may want to increase both the concurrent_writes and reads in the yaml file to take advantage of the extra IO. Same for the compaction settings, comments in the yaml file will help. With SSD and 10GbE you can easily hold more data on each node. Typically we advise 300GB to 500GB per node with HDD and 1GbE, because of the time repair and node replacement takes. With SSD and 10GbE it will take less, and even less if you are using SSD. If you feel like being thorough add repair and node replacement (all under load) to your test lineup. Hope that helps. ----------------- Aaron Morton Freelance Cassandra Developer New Zealand @aaronmorton http://www.thelastpickle.com On 20/02/2013, at 1:44 PM, Brandon Walsh <brandon_9021...@yahoo.com> wrote: > I have a 5 node cluster and currently running ver 1.2. Prior to full scale > deployment, I'm running some benchmarks using YCSB. From a hadoop cluster > deployment we saw an excellent improvement using higher speed networks. > However Cassandra does not include network latencies and I would like to > understand how we can capture network latencies between a 1GbE and 10GbE for > ex. As of now all the graphs look the same. We will soon be adding SSD's and > was wondering how Cassandra can utilize the 10GbE and the SSD's and if there > are specific tuning that is required.
