A number of NVR manufacturers are beginning to take advantage of the new 3TB & 4TB Enterprise hard drives, to cram as much recording storage space as possible into their hardware's existing footprint.
But are there downsides to this approach?
The first obvious one that strikes me is 'having too many eggs in one basket' - ie if a 4TB (non-RAID) drive fails (yes even Enterprise drives can fail!) the amount of video evidence lost is significantly more.
RAID overhead. The rule of thumb that in a RAID-5 config you lose the capacity of one drive (plus a bit more) means that 32TB, configured as 8 x 4TB HDDs, will yield roughly 28TB at RAID-5, whereas the same config using 16 x 2TB drives will give you 30TB useable.
Another less obvious potential downside might be performance. And I say 'might' because it would need benchmarking first (hint - John?). Take the above example of 32TB RAID storage built on either 8 vs 16 HDDs. Fewer physical drives means more data r/w per drive for a set number of cameras/frame rate/resolution etc. Exacq Technologies note in their performance benchmarking KB that:
"Minimum disk quantity: Servers are tested with a typical disk quantity for each server model ..... Video storage is usually limited by disk input/output capacity; increasing the disk quantity increases the server's video storage rate."
Be interested to hear what others have to say on this topic.