Physical machines unless you're running your cluster in the cloud (AWS/etc).

Reason is simple: Look how Cassandra scales and provides redundancy.  

Aaron Turner
http://synfin.net/         Twitter: @synfinatic
https://github.com/synfinatic/tcpreplay - Pcap editing and replay tools for Unix & Windows
Those who would give up essential Liberty, to purchase a little temporary
Safety, deserve neither Liberty nor Safety. 
    -- Benjamin Franklin



On Wed, Sep 11, 2013 at 4:21 PM, Shahab Yunus <shahab.yunus@gmail.com> wrote:
Hello,

We are deciding whether to get VMs or physical machines for a Cassandra cluster. I know this is a very high-level question depending on lots of factors and in fact I want to know that how to tackle this is and what factors should we take into consideration while trying to find the answer.

Data size? Writing speed (whether write heavy usecases or not)? Random ead use-cases? column family design/how we store data? 

Any pointers, documents, guidance, advise would be appreciated.

Thanks a lot.

Regards,
Shahab