My data disks on two of my nodes are RAID-5, just because of circumstances. My other nodes are JBOD. I don't notice any real difference, but I haven't strongly benched it.
IanOn Mon, May 24, 2010 at 2:45 PM, Jonathan Ellis <firstname.lastname@example.org> wrote:
I can think of at least 2 clusters running 32GB boxes with single
Cassandra processes on each. (16 seems to be more common.) At 64 I
would seriously consider multiple processes per machine. You'd want
to configure a Snitch such that same-machine boxes were considered the
same rack, there is no separate closeness level of same machine.
At 32 I think you're fine with one process. Watch for latency spikes
and see how it goes.
I would run raid 10 on the data disks if you can afford giving up the
space, otherwise raid0. I don't know that anyone's tested raid5.
On Sun, May 23, 2010 at 3:30 PM, Aaron McCurry <email@example.com> wrote:
> I am planning on setting up a Cassandra cluster on a small 16 node cluster
> (possibly 32 way). Each machine has 8 cores 32 Gig of ram and 8 hds. My
> first thought is to setup one of those hds for the commit log, 6 for data
> and leave one for the OS. However I do have a concern about best utilizing
> my memory, should I run a larger heap? Should I run several cassandra
> processes on the same box?
> My concern about the larger heap is because GC's typically get slower. And
> if I run several procs, does cassandra realize that it's the same box for
> replication purposes?
> I do have other hd conf options, hardware RAID 0,1,or 5.
> Just looking for some general configuration options as well as some real
> world successes with similarly sized hardware. Thanks!
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support