One of the most common problems people have with hard disks, especially when trying to
add a new hard disk to an older system, is the frustration of finding that not all of the
hard disk is actually accessible. This is almost always due to BIOS and operating system
issues that are a result of short-sighted planning done by the people that invented hard
disk structures, access routines and operating systems many years ago. In some cases they
are due to actual hardware or software bugs that are not detected until hard disks grow in
size beyond a certain point.
Fortunately, there are now solutions to most of these problems. This section takes a
complete look at these issues so you can finally understand what these barriers are all
about. Hopefully. 
And then also hopefully, solve the problem through hardware and
software changes.
Each of the barriers is described in its page title with a name that briefly summarizes
the reason for the barrier, and also the capacity figures generally associated with that
barrier. The capacity limits are given in both decimal (GB) and binary (GiB) formats since
some people look for specific decimal or binary numbers when identifying a size barrier.
Note: Most of the issues
discussed here are due to BIOS issues, and hence of relevance primarily to IDE/ATA hard
disks and not SCSI disks. Some though are also relevant for SCSI drives, especially ones
that are due to operating system limits.
Note: The pages in this
section are focused primarily on explaining the nature of the various hard disk barriers
and how they come about. To avoid duplication, I do not discuss how to deal with size
barriers here, because the techniques are common to many different barrier types. Look at this section for details on overcoming size barriers.
Next: Older Size Barriers
