There is no definite standard sizing for SPNAF. The file size, file type, user access rate, and server hardware specifications create different variations that may affect the SPNAF server’s performance. Determining the capacity or size of SPNAF server depends on the following variables:

•  VSCAN request coming from the filer - This value depends on network traffic and average size of scanned files.
• Handling capacity of the SPNAF scanner - This indicates the quantity of VSCAN request that can be processed by the SPNAF scanner depending on the number of CPU core.

To give you a rough estimation in SPNAF sizing:

1. Calculate the maximum VSCAN requests by dividing the network traffic limitation by the average size of scanned files.
   For example, if the average file size is 1MB and the network traffic limitation is set to 2.5GB per second, the maximum number of VSCAN request is 2560 requests per second.
   

   2.5GB per second / 1MB = 2560 requests per second

2. Calculate the SPNAF scanner’s handling capacity.
1. Determine the number of core CPU and multiply it by 2 to get the number of SPNAF scanner core.
   If there are 5 core CPU, it means that the SPNAF scanner has 10 cores.
   

   5 core CPU x 2 = 10 cores in the SPNAF scanner

2. Compute for the number of scan threads in the SPNAF scanner by multiplying the number of SPNAF scanner cores by 2, and then add 2.
   If there are 10 cores in the SPNAF scanner, it means that there are 22 scan threads.
   

   (10 cores in the SPNAF scanner x 2) + 2 = 22 scan threads

3. Multiply the number of scan threads by 5, assuming that each thread can handle 5 scan requests per second.
   If there are 22 scan threads, it means that the SPNAF scanner can manage 110 requests per second.
   

   5 scan requests per second x 22 scan threads = 110 requests per second

3. Divide the number of VSCAN requests from Step 1 by the SPNAF scanner handling capacity from Step 2. The result gives an idea how many SPNAF scanner servers are necessary.
   If there are 110 VSCAN requests and 2,560 requests per second, the required number of SPNAF scanner is 23.27, rounded-off to 24.
   

   2560 requests per second / 110 VSCAN requests = 23.27 scan servers

In this example, around 24 SPNAF virtual machine scan servers are required. If a physical server offers 20 cores, it can support 2 SPNAF servers with 10 cores each. Therefore, 12 physical servers will be necessary to manage 24 SPNAF scan servers.

VSCAN requests would not reach as high as 2,560 requests per second in a real situation. The example above was only based on an average file size of 1MB. It is still important to calculate the average file size as well as the peak network traffic based on an existing setup to produce a more accurate and realistic estimate of the required SPNAF scan servers.