Large filesystems and files caught many backup products by surprise. For many years, 4-GB filesystems with a maximum of 2-GB files ruled the land. This is because none of the operating systems allowed anything larger. Then came 32-bit operating systems and the terabyte filesystem. It wasn’t long after that that some vendors were announcing the ability to create terabyte files. This caused a major problem with some backup vendors, because many design decisions were made assuming there was a 4-GB limit.

There are a few things to consider when investigating if a given product can handle large files and filesystems. Does the vendor have any hardcoded limits that say a file can’t be any bigger than n bytes? Do they have problems if a filesystem (or file) is bigger than a volume?