[one-users] Queries regarding Storage Backend for DataStore

[ngurjar at neeleshgurjar.co.in]

Hi,
I am planning to setup OpenNebula 4.10 for Cloud Hosting.
In beginning I will be hosting 50 VMs of 2 vCPU with 40GB SSD Storage 
and OS will be Linux.

- Very first is how actually these datastore works in comparison with 
Cinder and Glance of OpenStack ?
- Which Datastore I can put on faster connectivity and which on slower?
- Suppose I launched 2 VMs from one image, where the images are stored 
of Both VMs?
In OpenStack I need to create Volume and attached as a RootDisk to 
instance, how should I go ahead in OpenNebula?
- How to calculate required IOPS to decide Storage Backend eg. Number of 
Drives, RAID level, Connectivity, etc.
- I was planning to use iSCSI with Nexenta based storage. Is that ok or 
should I go with Ceph ? will Ceph or NFS give performance ?
- Any suggestions to design the storage backend for DataStore.
- Do I need fiber connectivity between Compute Nodes and Storage ?

Regards
Neelesh Gurjar