Re: Effective allocation of multiple disks

[B. Todd Burruss]

with the file sizes we're talking about with cassandra and other 
database products, the stripe size doesn't seem to matter.  i suppose 
there may be a modicum of overhead with a small stripe size, but i'm not 
sure.  mine is set to 128k, which produced the same results as 16k and 256k.

i will say the number of drives within the RAID 0 setup does seem to 
matter.  more you have the more parallelism you can get with a good RAID 
controller.

Eric Rosenberry wrote:
Based on the documentation, it is clear that with Cassandra you want 
to have one disk for commitlog, and one disk for data.

My question is: If you think your workload is going to require more io 
performance to the data disks than a single disk can handle, how would 
you recommend effectively utilizing additional disks?

It would seem a number of vendors sell 1U boxes with four 3.5 inch 
disks.  If we use one for commitlog, is there a way to have Cassandra 
itself equally split data across the three remaining disks?  Or is 
this something that needs to be handled by the hardware level, or 
operating system/file system level?

Options include a hardware RAID controller in a RAID 0 stripe (this is 
more $$$ and for what gain?), or utilizing a volume manager like LVM.

Along those same lines, if you do implement some type of striping, 
what RAID stripe size is recommended?  (I think Todd Burruss asked 
this earlier but I did not see a response)

Thanks for any input!

-Eric