We currently have a server system that's been a little cobbled together by various IT people.
Current system:
XenServer 6.2 host with 3 operational VMs
- OES11
- Windows 2012
- Windows 2012 with domain services
The server hardware is a "white box" with 8 SAS drives in RAID10. By the time this server was built, we had almost run out of space, so a NAS box was added on - running as an iSCSI SAN. This primarily contains the less active data.
We have had numerous issues with this hardware that no-one seems able to identify - the server re-boots every Saturday at 11am, often with a couple of follow-up restarts.

To the point, I am looking at starting over.
I've seen with OES2015 sp1, you can install a two node cluster. I was thinking of this as a way to possibly use cheaper hardware as the redundancy would be in having a failover to a separate server. By cheaper, I mean perhaps a Xeon chip on a standard motherboard, good quality single power supply etc. with an extra network card.
Storage would be an iSCSI SAN through a gigabit switch (HP Procurve) to a couple of NAS boxes setup as iSCSI targets. I figured these could be mirrored NSS pools.
As I understand it, the VMs would run off NSS pool...
OES 2015sp1 host
- OES 2015sp1 file server
- Windows 2012/16
- Windows 2012/16 with domain services

One of the Windows servers runs a small database and service that indexes the files stored through the OES11 server.
We have about 25 users. Primarily running Win10.

Does the above seem feasible?
Our active data is currently stored on SAS drives within the main server box. Would there be much additional latency expected for file access? Some files are up to 300MB.

On another note, we have a satellite office with 4 users. They access files over a VPN directly. This is a little slow even with fibre internet.
We want to set up a replica of the data in that office, so it would be accessed locally.
In a stretched cluster with mirrored NSS pools as mentioned above, I understand that when writing data, it must complete all writes before moving to the next, so everything would slow down to the slowest link.
Is there a way to do this that locks files when opened at one site and doesn't release until replication occurs?

We have spoken to a number of IT companies, who just tell us to change to Windows.
Even had one that was "Novell Partner" tell us that OES was obsolete and that we could just use Ubuntu as a SAMBA box.

There're other services that we've had access to and never set up i.e. Zenworks, Filr, iPrint etc. Just can't find anyone to help with setup.
We're in Perth, Western Australia.