The R710 are the old servers and not used anymore the current servers are the R520.
You should never run the OS on a RAID5 set. I've used similar servers but put the OS/Program Files on a RAID1 set and packed the rest full of 3TB drives in a RAID5 configuration for video storage. Works great for small-medium installations. For larger/high bandwdith applications you might want to go with a RAID50/RAID60 application for faster disk space or save to fast SAS/SCSI drives and archive off every so often (like Milestone).
I doubt they are running the OS on the RAID array, although confirmation would be nice. The Dell R520 provides 8 drive bays, which would allow 1 to be used for the OS and the other 7 for data.
<edit> Or as Jason suggests, 2 bays setup as a RAID 1 for the OS/Program Files and the other 6 as a RAID 5 for data.<edit>
Why should a customer pay a much higher amount for the older dell series when the newer R720 with latest and better configuration is available at a much cheaper price.
Except that the ones direct from Dell are sauceless; by the time you add in your external saucepack you're looking at roughly the same number, though with one less drive bay...
"Unless you have direct experience with Avigilon NVRs, no more comments from you."
John - Not meaning to be argumentative, but Undisclosed A Integrator quickly turned the conversation to a general discussion about server configuration and internal vs. external storage, which is mostly what I've been responding to and have plenty of experience with.
I'll hold off on the saucy comments and anything Avigilon NVR specific. :)
They are no longer an R720, but now a R510 (or 520, cant remember)
I found out the hard way as we were using 3 nics in the 720's and the new NVR2's only come with 2, so i had to go out and buy a 2 port nic.
My personal experience is that if you dont need the 4hr response warranty, you can get a cheaper dell yourself. Ive started building our own based on the intel server chassis, where I can sell a 36TB NVR for the same price as an Avigilon 21TB.
As for the 21TB NVR's. Ive just had to nuke a raid array as the rebuild failed, and would not complete. It comes from Avigilon with a 50GB partition for windows and then a 19.5TB partition for storage on the same raid 5 array. After the nuke it got changed to raid 6.
TL:DR - NVR2's are now Dell R510 (or 520), and you should change the default config to RAID6 before deploying.