Date: Fri, 27 Aug 2021 16:38:18 +0200 From: Christian Groessler <chris@groessler.org> To: freebsd-questions@freebsd.org Subject: Re: Paritioning scheme on MBR disk doubts Message-ID: <def95f23-f82b-7a8f-0c5d-814bf7b80bb5@groessler.org> In-Reply-To: <20210827064821.0678b4da@archlinux> 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> <20210827064821.0678b4da@archlinux>
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On 8/27/21 6:48 AM, Ralf Mardorf wrote: > 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) The first sector of an extended partition has the same layout as the MBR.
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