Editing SD card (section)

====MBR and FAT====
{{More citations needed|section|date=September 2023}}
Most SD cards ship preformatted with one or more [[Master boot record|MBR partitions]], where the first or only partition contains a [[file system]]. This lets them operate like the [[hard disk]] of a [[personal computer]]. Per the SD card specification, an SD card is formatted with MBR and the following file system:

* For SDSC cards:
** Capacity of less than 32,680 logical sectors<!-- This is the exact condition as per the SD card spec. For operating systems to properly recognize this as FAT12, the cluster values used on the resulting volume must not be outside the range 002h..FF5h, a condition normally (but not necessarily) met implicitly when applying standard logical geometries on a FAT filesystem with less than 32680 logical sectors. We mention the logical sector count rather than the allowed cluster range here as this article is about SD cards specifically. --> (smaller than 16&nbsp;MB{{efn|name="here, MB = 1024"|reference=here, MB = 1024<sup>2</sup> B}}): [[FAT12]] with partition type [[Partition type#PID 01h|01h]] and [[BPB 3.0]] or [[EBPB 4.1]]<ref name="SDG_2000_SD-P2-V1.0">{{cite book
|title=SD Memory Card Specifications – PART 2 FILE SYSTEM SPECIFICATION – Version 1.0
|author=<!-- Staff writer(s); no by-line -->
|publisher=SD Group, Matsushita Electric Industrial Co., Ltd. (MEI), SanDisk Corporation, Toshiba Corporation
|date=February 2000
|version=1.0}}</ref>
** Capacity of 32,680 to 65,535 logical sectors (between 16&nbsp;MB and 32&nbsp;MB):{{efn|name="here, MB = 1024"}} [[FAT16]] with partition type [[Partition type#PID 04h|04h]] and [[BPB 3.0]] or [[EBPB 4.1]]<ref name="SDG_2000_SD-P2-V1.0"/>
** Capacity of at least 65,536 logical sectors (larger than 32&nbsp;MB):{{efn|name="here, MB = 1024"}} [[FAT16B]] with partition type [[Partition type#PID 06h|06h]] and [[EBPB 4.1]]<ref name="SDG_2000_SD-P2-V1.0"/>
* For SDHC cards:
** Capacity of less than 16,450,560<!-- CHS: 0..1023 / 0..254 (but not 255!) / 1 (but not 0!)..63 -> limit: 1024x255x63 = 16450560 --> logical sectors (smaller than 7.8&nbsp;GB): [[FAT32]] with partition type [[Partition type#PID 0Bh|0Bh]] and [[EBPB 7.1]]
** Capacity of at least 16,450,560 logical sectors (larger than 7.8&nbsp;GB): [[FAT32]] with partition type [[Partition type#PID 0Ch|0Ch]] and [[EBPB 7.1]]
* For SDXC cards: [[exFAT]] with partition type [[Partition type#PID 07h|07h]]

Most consumer products that take an SD card expect that it is partitioned and formatted in this way. Universal support for FAT12, FAT16, FAT16B and FAT32 allows the use of SDSC and SDHC cards on most host computers with a compatible SD reader, to present the user with the familiar method of named files in a hierarchical directory tree.{{citation needed|date=September 2023}}

On such SD cards, standard utility programs such as Mac OS X's "{{Nowrap|[[Disk Utility]]}}" or Windows' [[SCANDISK]] can be used to repair a corrupted filing system and sometimes recover deleted files. [[Defragmentation]] tools for FAT file systems may be used on such cards. The resulting consolidation of files may provide a marginal improvement in the time required to read or write the file,<ref name="Fragmentation_and_Speed">{{Citation | url = https://www.sdcard.org/developers/overview/speed_class/ | title = Fragmentation and Speed | date = 11 December 2020 | publisher = SD Card | access-date = 21 November 2011 | archive-date = 3 June 2018 | archive-url = https://web.archive.org/web/20180603051813/https://www.sdcard.org/developers/overview/speed_class/ | url-status = live }}</ref> but not an improvement comparable to defragmentation of hard drives, where storing a file in multiple fragments requires additional physical and relatively slow, movement of a drive head.{{citation needed|date=September 2023}} Moreover, defragmentation performs writes to the SD card that count against the card's rated lifespan. The write endurance of the physical memory is discussed in the article on [[Flash memory degradation|flash memory]]; newer technology to increase the storage capacity of a card provides worse write endurance.{{citation needed|date=September 2023}}

When reformatting an SD card with a capacity of at least 32&nbsp;MB{{efn|name="here, MB = 1024"}} (65,536 logical sectors or more), but not more than 2&nbsp;GB,{{efn|name="GiB"}} [[FAT16B]] with partition type [[Partition type#PID 06h|06h]] and [[EBPB 4.1]]<ref name="SDG_2000_SD-P2-V1.0"/> is recommended if the card is for a consumer device. (FAT16B is also an option for 4&nbsp;GB cards, but it requires the use of 64&nbsp;KB [[cluster (file system)|clusters]], which are not widely supported.) FAT16B does not support cards above 4&nbsp;GB{{efn|name="GiB"}} at all.

The SDXC specification mandates the use of [[Microsoft]]'s [[proprietary format|proprietary]] [[exFAT]] file system,<ref name="engadget_sdxc_2t_300m">{{cite web | url = https://www.engadget.com/2009/01/07/sdxc-memory-cards-promise-2tb-of-storage-300mbps-transfer/ | title = SDXC memory cards promise 2 TB of storage, 300 MBps transfer | publisher = Engadget | date = 2009-01-07 | access-date = 2010-08-22 | archive-date = 2010-02-11 | archive-url = https://web.archive.org/web/20100211152502/http://www.engadget.com/2009/01/07/sdxc-memory-cards-promise-2tb-of-storage-300mbps-transfer | url-status = live }}</ref> which sometimes requires appropriate drivers (e.g. <code>exfat-utils</code>/<code>exfat-fuse</code> on Linux).