512 sectors for read-ahead. Are your new fancy SSD drives using large sectors? If your read-ahead is really reading 512 x 4KB per random IO, then that 2 MB per read seems like a lot of extra overhead.
-Bryan On Thu, May 16, 2013 at 12:35 PM, Keith Wright <kwri...@nanigans.com> wrote: > We actually have it set to 512. I have tried decreasing my SSTable size > to 5 MB and changing the chunk size to 8 kb > > From: Igor <i...@4friends.od.ua> > Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org> > Date: Thursday, May 16, 2013 1:55 PM > > To: "user@cassandra.apache.org" <user@cassandra.apache.org> > Subject: Re: SSTable size versus read performance > > My 5 cents: I'd check blockdev --getra for data drives - too high values > for readahead (default to 256 for debian) can hurt read performance. > >
