What you have, basically, is two high-level problems:
- How to get the recursive size of a folder and all its contents (including sub-folders).
- How to solve problem #1 across a large number of machines on a network.
To solve #1, I suggest the easiest way is to use the du utility. This is a UNIX command-line utility that has a windows port; Grab it from: http://gnuwin32.sourceforge.net/packages/coreutils.htm
By default, du recursively scans from the current directory and prints the sizes and names. What you want is the summary as if you right-clicked the folder and did properties. So run it like this
du -s Note the output is in bytes which is convenient for Excel work.
To solve #2 I suggest that you map a network drive to each computer in turn, run the du command (but appending to a file) and then do a sum in Excel. The du command will look like this:
du -s >> backupSize.txt by default, the du output columns are tab-separated which imports easily into Excel.
You will have to solve the details of getting all those folders shared, making sure all the machines are available on the network, writing a batch file with a foreach style loop, and summing in Excel.