What is the difference between scylla read path and cassandra read path?

Question

What is the difference between Scylla read path and Cassandra read path? When I stress Cassandra and Scylla then Scylla read performance poor by 5 times than Cassandra using

Answer 1

Both databases use LSM tree but Scylla has thread-per-core architecture on top plus we use O_Direct while C* uses the page cache. Scylla also has a sophisticated IO scheduler that makes sure not to overload the disk and thus scylla_setup runs a benchmark automatically to tune. Check your output of it in io.conf.

There are far more things to review, better to send your data to the mailing list. In general, Scylla should perform better in this case as well but your disk is likely to be the bottleneck in both cases.