*nodetool setcompactionthroughput 0* Will only affect future compactions, not the ones that are currently running.
All the best, [image: datastax_logo.png] <http://www.datastax.com/> Sebastián Estévez Solutions Architect | 954 905 8615 | sebastian.este...@datastax.com [image: linkedin.png] <https://www.linkedin.com/company/datastax> [image: facebook.png] <https://www.facebook.com/datastax> [image: twitter.png] <https://twitter.com/datastax> [image: g+.png] <https://plus.google.com/+Datastax/about> <http://feeds.feedburner.com/datastax> <http://goog_410786983> <http://www.datastax.com/gartner-magic-quadrant-odbms> DataStax is the fastest, most scalable distributed database technology, delivering Apache Cassandra to the world’s most innovative enterprises. Datastax is built to be agile, always-on, and predictably scalable to any size. With more than 500 customers in 45 countries, DataStax is the database technology and transactional backbone of choice for the worlds most innovative companies such as Netflix, Adobe, Intuit, and eBay. On Fri, Jan 15, 2016 at 4:40 PM, Jeff Ferland <j...@tubularlabs.com> wrote: > Compaction is generally CPU bound and relatively slow. Exactly why that is > I’m uncertain. > > On Jan 15, 2016, at 12:53 PM, Kai Wang <dep...@gmail.com> wrote: > > Hi, > > I am trying to figure out the bottleneck of compaction on my node. The > node is CentOS 7 and has SSDs installed. The table is configured to use > LCS. Here is my compaction related configs in cassandra.yaml: > > compaction_throughput_mb_per_sec: 160 > concurrent_compactors: 4 > > I insert about 10G of data and start observing compaction. > > *nodetool compaction* shows most of time there is one compaction. > Sometimes there are 3-4 (I suppose this is controlled by > concurrent_compactors). During the compaction, I see one CPU core is 100%. > At that point, disk IO is about 20-25 M/s write which is much lower than > the disk is capable of. Even when there are 4 compactions running, I see > CPU go to +400% but disk IO is still at 20-25M/s write. I use *nodetool > setcompactionthroughput 0* to disable the compaction throttle but don't > see any difference. > > Does this mean compaction is CPU bound? If so 20M/s is kinda low. Is there > anyway to improve the throughput? > > Thanks. > > >
