If he starts with u2 and his hard drive (or RAID array) has a 1K block size, the limit will be 1T (1024*1024*1K = 1T). 1T was the limit for me at RHEL3/ESu2 even though physically my array has about 70G beyond that limit:
Disk /dev/sda: 2199.0 GB, 2199014866944 bytes 64 heads, 32 sectors/track, 2097144 cylinders Units = cylinders of 2048 * 512 = 1048576 bytes