It seems you are intending to license the ESX(i) hosts for at least HA meaning Essentials Plus. Vmware cost will be MUCH higher to gain FT too. However HA will need shared storage to function, and if looking at that then this is just moving the point of failure - there is only a benefit if you get a truely high available storage solution, which will mutiply the cost of the solution many times.
Anyway, considering all that I would look at Veeam Essentials bundle backups and still Essentials Plus for vmware since this includes (excellent) support. Veeam will give you monitoring components within the VMs and the ability, in future perhaps, to replicate to a second datacentre. All for a literally give-away price (note I'm in no way associated with Veeam BTW).
The core advantages of Veeam over the basic free scripts are that it uses change-block-tracking for both backups and replication which *greatly* improves performance and makes possible replication of multi-TB VMs, and secondly using compression & de-duplication it is feasible to keep many generations of backups online on spinning storage.
For a backup target you might consider repurposing an older server with a bunch of new SATA drives to keep the cost down.
Also on the planned RAID levels -
- Don't waste two spindles for ESX(i) install since it has barely any IO footprint
- Don't use RAID-0, ever
- Ensure the controller has battery-backed write-cache and this is enabled in write-back mode. This is *essential*.
Your servers will perform much better using an 8-drive RAID-10 volume (keep a spare on the shelf!).
Hope that helps.
