Memory Technology Device: Difference between revisions

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{{Short description|Type of device file in Linux for interacting with flash memory}}

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[[File:Macronix MX29LV320ATTC-70G 20110908.jpg|thumb|150px|Flash-[[EEPROM]] in a Router - a true MTD]]

A '''Memory Technology Device''' (MTD) is a type of [[device file system#Devices|device file]] in [[Linux]] for interacting with [[flash memory]]. The MTD subsystem was created to provide an [[abstraction layer]] between the hardware-specific device drivers and higher-level applications. Although character and block device files already existed, their semantics don't map well to the way that flash memory devices operate.

[[File:Macronix MX29LV320ATTC-70G 20110908.jpg|thumb|150px|Flash-[[EEPROM]] in a Router -– a true MTD]]

[[USB stick]]s, [[MultiMediaCard|MMC]]s, [[Secure Digital|SD]]s, [[CompactFlash]]es and other popular removable devices should not be confused with MTDs. Although they contain flash memory, this is hidden behind a [[block device]] interface using a [[Flash Translation Layer]].<ref>{{cite web | url=http://www.linux-mtd.infradead.org/doc/general.html#L_overview | title=Memory Technology Device Overview | accessdate=1 September 2012}}</ref>

A '''Memory Technology Device''' (MTD) is a type of [[deviceDevice file system#Devices|device file]] in [[Linux]] for interacting with [[flash memory]]. The MTD subsystem was created to provide an [[abstraction layer]] between the hardware-specific device drivers and higher-level applications. Although character and block device files already existed, their semantics don't map well to the way that flash memory devices operate.

[[USB stick]]s, [[MultiMediaCard|MMC]]s, [[Secure Digital|SD]]s, [[CompactFlash]]es and other popular removable devices shouldare not be confused with MTDs. Although they contain flash memory, this is hidden behind a [[block device]] interface using a [[Flash Translation Layer]] and not directly interfacing with the kernel.<ref>{{cite web | url=http://www.linux-mtd.infradead.org/doc/general.html#L_overview | title=Memory Technology Device Overview | accessdate=1 September 2012}}</ref>

When using an MTD, the use of an MTD aware file system such as [[JFFS2]] or [[YAFFS]] is recommended. The MTD subsystem exports block devices as well, which allows the use of common filesystem like ext4. However, using an MTD this way is not recommended since there is neither detection of bad blocks nor any kind of wear leveling.

When using an MTD, the use of an MTD aware file system such as [[UBIFS]], [[JFFS2]] or [[YAFFS]] is recommended. The MTD subsystem exports block devices as well, which allows the use of common filesystem like ext4. However, using an MTD this way is not recommended since there is neither detection of bad blocks nor any kind of wear leveling.

== See also ==

* [[Linux on embedded systems]]

MTDs don't address to the kernel like traditional storage devices ([[Solid State Drive]], [[Hard Disk Drive]]...) using [[Logical block addressing|LBA]]s, but rather using offsets and sizes.

==References==

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== External links ==

* http://www.linux-mtd.infradead.org

{{Linux kernel}}

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[[Category:Solid-state computer storage media]]

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