One of the problems users face when trying out Virtual Infrastructure solutions is the requirement of centralized storage in order to utilize the enterprise class goodies–functions like Vmotion, HA and DRS in VMware for example. I ran into this when first constructing a lab environment for my team. SAN storage is not cheap and quite hard to price justify when setting up a small scale (20 – 30 vms) virtualized testing environment.
Building SAN costs into the planning for production rollouts is easier to justify for security, performance and availability but still not what I would consider a slam dunk since it will likely be the most expensive hardware you will be purchasing for your virtualization rollout… unfortunately it is a bit like buying insurance; you simply have no choice… you must have centralized storage to have any kind of high availability and redundancy in your virtual environment.
However, there are relatively easy and inexpensive central storage solutions based on opensource iSCSI target software from vendors such as: Openfiler or FreeNAS. I have tried both (with help from some of my team members) but found them both to be a bit difficult to setup and configure. Another easy solution that I have setup and am using quite successfully right now is a simple NFS share setup on a Windows 2003 Server with some large disks (two 750GB for my primary NAS server). This is an easy enough solution to setup for anyone with decent Windows admin experience and simply requires that you setup “Windows Services for UNIX” on your designated target server and follow the instructions from this excellent article on the VMGuru site. I did find that a couple of the steps were a bit confusing and may take a stab at updating the instruction set at some point, but it is easy enough to figure out with a little trial and error.
An obvious advantage to setting up quick and easy NAS storage like this for your VI3 environment is cost. It does not require a high end server to simply provide NAS/NFS shares for VI3 and so far they have been extremely reliable and running continuously for a couple of months now on low-end Dell PowerEdge hardware (sub $1k server, $100 a disk, total of ~$1150 for 1.5TB of centralized storage). Security on the NAS server is pretty straightforward as well, just lock the system down to only allow Domain Admin access (assuming the server is in a domain). Vmotion, HA and DRS in VI3 all operate just fine with this type of central storage.
Another interesting security related bit I read about NFS datastores vs VMFS datastores is that an NFS datastore is not directly accessible to an enduser that is logged onto an ESX host whereas a VMFS datastore is. While the user will not have access to the raw VMDK files (Virtual Machine disk files) they would be able to glean information about the VM’s (which could potentially be a bad thing), with NFS this is a non-issue.