You can check cfstats to see what's the compression ratio. It's totally possible to have the values you're reporting as a compression ratio of 0.2 is quite common depending on the data you're storing (compressed size is then 20% of the original data).
Compaction throughput changes are taken into account for running compactions starting with Cassandra 2.2 if I'm correct. Your compaction could be bound by cpu, not I/O in that case. Cheers Le lun. 5 nov. 2018 à 20:41, Pedro Gordo <pedro.gordo1...@gmail.com> a écrit : > Hi > > We have an ongoing compaction for roughly 2.5 TB, but "nodetool status" > reports a load of 1.09 TB. Even if we take into account that the load > presented by "nodetool status" is the compressed size, I very much doubt > that compression would work to reduce from 2.5 TB to 1.09. > We can also take into account that, even if this is the biggest table, > there are other tables in the system, so the 1.09 TB reported is not just > for the table being compacted. > > What could lead to results like this? We have 4 attached volumes for data > directories. Could this be a likely cause for such discrepancy? > > Bonus question: changing the compaction throughput to 0 (removing the > throttling), had no impacts in the current compaction. Do new compaction > throughput values only come into effect when a new compaction kicks in? > > Cheers > > Pedro Gordo > -- ----------------- Alexander Dejanovski France @alexanderdeja Consultant Apache Cassandra Consulting http://www.thelastpickle.com
