This due to hardware limitations of some PC motherboard/disk configurations.

OS RELEASE              SINGLE FILE             FILE SYSTEM
===============         ===========             ===========
4.1.x                      2 GB                     2 GB
4.1.x + ODS                2 GB                     1 TB
Solaris 2.0-2.5.1          2 GB                     1 TB
Solaris 2 + SDS            2 GB                     1 TB
Solaris 2.6 - Sol 9        ~800 GB                  1 TB

A single file of Solaris 2.6 is limited to "about" 800 GB because the
file MUST fit inside a file system. The file system is nominally 1 TB,
but in fact one must create enough overhead in such a large file system
that the largest single file ends up being "about" 800 GB.
(part of this is a bug, but even if bug-free a single file can't be 1 TB)

Note that in Solaris 2.6, the swap and tmpfs file system are still limited
to 2 GB.  This is not the total amount of swap, just a limit per slice or per
swap file.  There can be multiple swap slices or files totaling more than 2Gb.
Also, any higher rev. of Solaris running 32 bit kernel has the above limit.
Solaris 7 or higher running 64 bit kernel doesn't  Have that limit. See Sol 8
swap (1M) manpage (USAGE paragraph) for the new limits.

Please note that the root file system is limited to ~2 GB on
all but Ultras due to an OBP limitation (~1 GB on systems with OBP
versions 1.0->2.6).