The number of mounts is limited by the number of bits allowed in the minor device number and the number of ports available (for NFS 1,2,3). On Linux <2.6, the minor device numbers were only 8 bits long, so you could have 255 NFS mounts. On 2.6 Linux the minor device numbers are 20 bits long, so in theory you could have 1048575 NFS mounts. You'd run out of network ports first though.
So, for 2.4 and below Linux kernels, it's 255. For 2.6 kernels you're never going to hit the limit unless you're doing something really, really mental.
P.S. I fail to see what could possibly be URGENT about this.
Last edited by ilikejam; 11-26-2009 at 05:15 AM.