The limit is higher than you'll be able to actually make use of.
I was able to get it to accept a value of 999999999, but at 1000000000, it threw ERROR : Invalid Parameter #3 : "/lev:1000000000"
. Presumably, this means that the parameter will accept numbers up to 9 decimal places long, but not 10, making the maximum value 1 less than a billion.
Of course, you'll run into path length limits long before that, and I frankly can't even begin to imagine a use for high values in the lev
parameter.
This done in Windows 7, SP1, with PowerShell 4, if anyone cares to check other OS and/or robocopy versions for comparison, though it seems like a thoroughly pointless exercise to me.
Behold my fearsome screenshot, which shows me trying to copy my C drive to a subfolder on the C drive. I cancelled the operation as quickly as I could, of course.
