Hi, Yoshi Thank you for your replay.
Of cause I read the document you linked, But I'm still confused about the deletion timing of the commit log segment files Because the total size of the commit log segment files grows until 3GB even if there are many memtable flushes. Anyway I'll check the deletion timing of the commit log segment files with changing the memtable size (memtable_heap_space_in_mb). Regards, Satoshi On Thu, Dec 8, 2016 at 5:56 PM, Yoshi Kimoto <yy.kim...@gmail.com> wrote: > That is probably because the relevant memtable is flushed to SSTable and > the content of the commit log is not required any more so it's rewinding. > > See: http://docs.datastax.com/en/cassandra/3.x/cassandra/ > dml/dmlHowDataWritten.html > > > > 2016年12月8日(木) 17:45 Satoshi Hikida <sahik...@gmail.com>: > >> Hi, >> >> I have a question about commit log. >> >> When commit log segment files are remove actually? >> >> I'm running a single node cluster for a few weeks to test C* performance. >> My simple test have been issuing only read and write requests to the >> cluster, then the data size (SSTables size) are increasing monotonously. >> >> Here are customized C* settings in my environment. >> - commitlog_total_space_in_mb: 8192 >> - memtable_flush_writers: 4 >> - memtable_heap_space_in_mb: 2048 >> >> And here is the node specs used in my environment. >> - CPU core: 4 >> - Memory: 16GB >> - SSD: 100GB * 2 (one for commit log, the other for data) >> >> In this case, I expected that the total size of the commit log segment >> files are increased up to 8GB. However, when the total size is >> increased up to 3GB, the commit log segment files are removed and >> total size reduced to around 250MB. >> >> I wonder why commit log segment files are removed before total size is >> increased up to 8GB(= commitlog_total_space_in_mb) ? Could anyone give >> me some advices? >> >> >> Regards, >> Satosh >> >> >> >>
