Everything is written to the commit log. In the case of a crash, cassandra recovers by replaying the log.
On Sat, Jul 20, 2013 at 9:03 AM, Mohammad Hajjat <haj...@purdue.edu> wrote: > Patricia, > Thanks for the info. So are you saying that the *whole* data is being > written on disk in the commit log, not just some sort of a summary/digest? > I'm writing 10MB objects and I'm noticing high latency (250 milliseconds > even with ANY consistency), so I guess that explains my high delays? > Thanks, > Mohammad > On Fri, Jul 19, 2013 at 2:17 PM, Patricia Gorla > <gorla.patri...@gmail.com>wrote: >> Kanwar, >> >> This is because writes are appends to the commit log, which is stored on >> disk, not memory. The commit log is then flushed to the memtable (in >> memory), before being written to an sstable on disk. >> >> So, most of the actions in sending out a write are writing to disk. >> >> Also see: http://www.datastax.com/docs/1.2/dml/about_writes >> >> Patricia >> >> >> On Fri, Jul 19, 2013 at 1:05 PM, Kanwar Sangha <kan...@mavenir.com> wrote: >> >>> “Insert-heavy workloads will actually be CPU-bound in Cassandra before >>> being memory-bound”**** >>> >>> ** ** >>> >>> Can someone explain why the internals of why writes are CPU bound ?**** >>> >>> ** ** >>> >>> ** ** >>> >> >> > -- > *Mohammad Hajjat* > *Ph.D. Student* > *Electrical and Computer Engineering* > *Purdue University*
