On Tue, 2010-12-07 at 21:25 -0500, Edward Capriolo wrote:
> The idea behind "micrandra" is for a 6 disk system run 6 instances of > Cassandra, one per disk. Use the RackAwareSnitch to make sure no > replicas live on the same node. > > The downsides > 1) we would have to manage 6x the instances of cassandra > 2) we would have some overhead for each JVM. > > The upsides ? > 1) Since disk/instance failure only degrades the overall performance > 1/6th (RAID0 you lost the entire node) (RAID5 still takes a hit when > down a disk) > 2) Moves and joins have less work to do > 3) Can scale up a single node by adding a single disk to an existing > system (assuming the ram and cpu is light) > 4) OPP would be "easier" to balance out hot spots (maybe not on this > one in not an OPP) > > What does everyone thing? Does it ever make sense to run this way? It might for read heavy loads. When I looked at this, it was pointed out to me it's simpler to run fewer bigger coarser nodes and take the entire node/server out when something goes wrong. Basically give each Cassandra a server. I wonder if it would be better to rethink compaction if that's what's driving the idea. It seems to what is biting everyone, along with GC. Bill
