Date: Fri, 27 Aug 2021 06:48:21 +0200 From: Ralf Mardorf <ralf-mardorf@riseup.net> To: freebsd-questions@freebsd.org Subject: Re: Paritioning scheme on MBR disk doubts Message-ID: <20210827064821.0678b4da@archlinux> In-Reply-To: <8ab9716c-fdc3-ad09-1883-8210b37ef520@groessler.org> References: <MW4PR01MB640175FEDE09CAD451A9AA0BC4C79@MW4PR01MB6401.prod.exchangelabs.com> <d21dc1de-87dc-8e45-260b-cf7baf23998a@holgerdanske.com> <MW4PR01MB6401DA1B3479DE69944C7D5BC4C79@MW4PR01MB6401.prod.exchangelabs.com> <8ab9716c-fdc3-ad09-1883-8210b37ef520@groessler.org>
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On Thu, 26 Aug 2021 20:53:25 +0200, Christian Groessler wrote:
>If I remember correctly, an extended partition can also only hold 4
>partitions. Of which one in turn can again be an extended partition
>which can hold 4 partitions. Of which one in turn can again be an
>extended partition... etc
That's incorrect.
"Master Boot Record (partition table)
In the MBR partition table (also known as DOS or MS-DOS partition
table) there are 3 types of partitions:
Primary
Extended
Logical
Primary partitions can be bootable and are limited to four partitions
per disk or RAID volume. If the MBR partition table requires more than
four partitions, then one of the primary partitions needs to be
replaced by an extended partition containing logical partitions within
it.
Extended partitions can be thought of as containers for logical
partitions. A hard disk can contain no more than one extended
partition. The extended partition is also counted as a primary
partition so if the disk has an extended partition, only three
additional primary partitions are possible (i.e. three primary
partitions and one extended partition). The number of logical
partitions residing in an extended partition is unlimited. A system
that dual boots with Windows will require for Windows to reside in a
primary partition.
The customary numbering scheme is to create primary partitions sda1
through sda3 followed by an extended partition sda4. The logical
partitions on sda4 are numbered sda5, sda6, etc. Tip: When partitioning
a MBR disk consider leaving at least 33 512-byte sectors (16.5 KiB) of
free unpartitioned space at the end of the disk in case you ever decide
to convert it to GPT. The space will be required for the backup GPT
header." -
https://wiki.archlinux.org/title/partitioning#Master_Boot_Record_(partition_table)
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