Server / Storage Design For 75-100 IP Cameras

Depends on your VMS and throughput needs.  As I use Avigilon most often I target direct attached or onboard storage.  With some other VMS I am more comfortable using a SAN/NAS for external storage.  Talk to the VMS vendor and they will make the best recommendation.  For example, if you are utilizing Milestone I would use a SAN/NAS all day long as long as the throughput is adequate.

We also do a lot of Avigilon and I would use one of the PRO servers with a 10GB link to the camera network which could handle 100 cameras without issue.   For storage expansion, my go to tech is fiber channel storage. 

Option 1...local storage or direct attached.

From a performance perspective, lets assume a 6Mbit/sec stream size which means the 100 cams will feed in appx 600Mbits of data.

Most of the VMS's I test in my lab can handle that in a single 'robust' server.  The hardware definition of 'robust' depends on the VMS which is why we test them in the lab.

The storage amount easily fits into a 12bay chassis with 8TB drives and RAID6.   Higher drive bay counts will increase storage performance as the spindle count grows and you can use smaller drive sizes which tend to be cheaper.

This leaves you the option of having a 'failover' machine for most VMSs (same horsepower but less storage).

The storage drives will fail at some point, so the storage path will suffer while the array rebuilds.   As long as you were not saturating the storage path, you will not notice this on a RAID6 array.

The expansion part should be planned for when the system is designed.   The extra cameras will need more horsepower and storage.

You could consider assigning a certain count to servers and add another one as the expansion occurs.   For example, use 64 cams on each server to start with...which puts you at two servers.    When you go beyond 128 cams you add another server.

The VMS selected should be able to see and manage all the servers added.

Option 2 ... centralized storage.

Using the SAN/NAS as a centralized storage target will bring extra network requirements to the table as well as managing the storage.

You will need to know the bandwidth requirements of each server feeding the array as well as considering what future BW will be needed.

The storage expansion process will depend on whose solution you use.   Each one will have a different way to expand the available storage to use for the servers.

Your choice will depend on what you want to deal with.

Take a look at Pivot3 and you will never look back.

We use Avigilon and have high-capacity NVR servers that I custom spec from Dell.  PowerEdge R730xd units with up to 84TB storage in a RAID 5 or RAID 6 configuration, an enterprise class RAID card (we use 1GB and 2GB cache cards), and I spec the flex bay drives to dedicate to the OS.

As others have pointed out, using multiple servers with some VMSs allows for configuration of failover recording.