A maximum of sixteen partitions per GPT disk may be for one or both of the following:
- compatibility with other BSD variants
- UNIX certification/conformance.
In theory, a GUID Partition Table (GPT) disk can have an unlimited number of partitions.
A Microsoft implementation of GPT allows a maximum of 128 partitions.
The OS X kernel, libraries, and utilities are drawn from a number of open source projects, including FreeBSD, GNU, NetBSD, and OpenBSD.
Some BSD variants have a maximum of sixteen partitions.
Mac OS X: Mac OS Extended format (HFS Plus) volume and file limits
Volume and file limits in Mac OS X
Maximum number of volumes (all Mac OS X versions): no limit …
- volumes per operating system
- not partitions per disk.
Expect the operating system to handle:
- thirty-two or more volumes spread across two or more disks
- and so on.
disklabel(8) OS X Manual Page (2004-09-03)
Frequently asked questions about the GUID Partitioning Table disk architecture (2009-08-04)
…The Microsoft implementation of GUID Partition Table is limited to 128 partitions. …
OS X Glossary (2010-07-09)
Berkeley Software Distribution. Formerly known as the Berkeley version of UNIX,
BSD is now simply called the BSD operating system. The BSD portion of Darwin is
based on 4.4BSD Lite 2 and FreeBSD, a flavor of 4.4BSD.
Unix 03 Conformance Release Notes (2010-09-01)
… FreeBSD, GNU, NetBSD, and OpenBSD … make an effort to
follow industry standards …
How-To Dual Boot FreeBSD, Linux, and OpenBSD with GNU Grub (undated but Copyright © 2000 - 2012)
… OpenBSD's disklabel allows up to 16 partitions. …
Register of Open Branded Products: five product standards for which Mac OS X Version 10.8 Mountain Lion is registered (2012-07-10)
BSD disklabel – Wikipedia (2013-01-27)
… BSD disklabels traditionally contain 8 entries for describing partitions.
These are, by convention, labeled alphabetically, 'a' through to 'h'. Some
BSD variants have since increased this to 16 partitions, labeled 'a' through to 'p'. …