You should give further information if you want an answer. What kind of instance it is ? Instance sore / EBS / Optimized EBS ? Do you try to read / write on this disk ? How much ? ...

With m1 xlarge we reached 40 MBps and now with a hi1.4xlarge we don't have reach any limit yet, and we have 100+ MBps.

My guess is that either you are writing (so no disk ops, because of memtables) or your client process data too slowly to use correctly your hardware.

Alain


2013/9/13 David Ward <david@shareablee.com>
I noticed on EC2, the c* nodes according to OpsCenter have never gone above 1.6-2.2MBps.  That seems abnormally low but I have no reference as to what is "normal" for cassandra on EC2 and curious what other people have seen according to OpsCenter for the "OS: Disk Throughput" metric.

Thanks,
   Dave