Actually, many SSD drives show much better performance for sequential write then random writes, so you may benefit from a separate drive  for commit logs.

On Mon, Sep 23, 2013 at 11:21 AM, Robert Coli <> wrote:
On Sun, Sep 22, 2013 at 4:02 PM, Shahryar Sedghi <> wrote:
This my first SSD experience. With  normal disks we separate commit log from data. We have 2 SSDs dedicated to Cassandra  I was wondering if we gain a better performance  if we put commit  log in one and data in another, or just use raid 0 to have both SSDs combined.

The primary win from separation comes when your head does not move while appending. As your SSDs have no heads, you do not get this win.