drivers/md/Kconfig - kernel/msm-4.9 - Gitiles

 #
 # Block device driver configuration
 #

 menuconfig MD
 	bool "Multiple devices driver support (RAID and LVM)"
 	depends on BLOCK
 	help
 	  Support multiple physical spindles through a single logical device.
 	  Required for RAID and logical volume management.

 if MD

 config BLK_DEV_MD
 	tristate "RAID support"
 	---help---
 	  This driver lets you combine several hard disk partitions into one
 	  logical block device. This can be used to simply append one
 	  partition to another one or to combine several redundant hard disks
 	  into a RAID1/4/5 device so as to provide protection against hard
 	  disk failures. This is called "Software RAID" since the combining of
 	  the partitions is done by the kernel. "Hardware RAID" means that the
 	  combining is done by a dedicated controller; if you have such a
 	  controller, you do not need to say Y here.

 	  More information about Software RAID on Linux is contained in the
 	  Software RAID mini-HOWTO, available from
 	  <http://www.tldp.org/docs.html#howto>. There you will also learn
 	  where to get the supporting user space utilities raidtools.

 	  If unsure, say N.

 config MD_AUTODETECT
 	bool "Autodetect RAID arrays during kernel boot"
 	depends on BLK_DEV_MD=y
 	default y
 	---help---
 	  If you say Y here, then the kernel will try to autodetect raid
 	  arrays as part of its boot process.

 	  If you don't use raid and say Y, this autodetection can cause
 	  a several-second delay in the boot time due to various
 	  synchronisation steps that are part of this step.

 	  If unsure, say Y.

 config MD_LINEAR
 	tristate "Linear (append) mode"
 	depends on BLK_DEV_MD
 	---help---
 	  If you say Y here, then your multiple devices driver will be able to
 	  use the so-called linear mode, i.e. it will combine the hard disk
 	  partitions by simply appending one to the other.

 	  To compile this as a module, choose M here: the module
 	  will be called linear.

 	  If unsure, say Y.

 config MD_RAID0
 	tristate "RAID-0 (striping) mode"
 	depends on BLK_DEV_MD
 	---help---
 	  If you say Y here, then your multiple devices driver will be able to
 	  use the so-called raid0 mode, i.e. it will combine the hard disk
 	  partitions into one logical device in such a fashion as to fill them
 	  up evenly, one chunk here and one chunk there. This will increase
 	  the throughput rate if the partitions reside on distinct disks.

 	  Information about Software RAID on Linux is contained in the
 	  Software-RAID mini-HOWTO, available from
 	  <http://www.tldp.org/docs.html#howto>. There you will also
 	  learn where to get the supporting user space utilities raidtools.

 	  To compile this as a module, choose M here: the module
 	  will be called raid0.

 	  If unsure, say Y.

 config MD_RAID1
 	tristate "RAID-1 (mirroring) mode"
 	depends on BLK_DEV_MD
 	---help---
 	  A RAID-1 set consists of several disk drives which are exact copies
 	  of each other.  In the event of a mirror failure, the RAID driver
 	  will continue to use the operational mirrors in the set, providing
 	  an error free MD (multiple device) to the higher levels of the
 	  kernel.  In a set with N drives, the available space is the capacity
 	  of a single drive, and the set protects against a failure of (N - 1)
 	  drives.

 	  Information about Software RAID on Linux is contained in the
 	  Software-RAID mini-HOWTO, available from
 	  <http://www.tldp.org/docs.html#howto>.  There you will also
 	  learn where to get the supporting user space utilities raidtools.

 	  If you want to use such a RAID-1 set, say Y.  To compile this code
 	  as a module, choose M here: the module will be called raid1.

 	  If unsure, say Y.

 config MD_RAID10
 	tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
 	depends on BLK_DEV_MD && EXPERIMENTAL
 	---help---
 	  RAID-10 provides a combination of striping (RAID-0) and
 	  mirroring (RAID-1) with easier configuration and more flexible
 	  layout.
 	  Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
 	  be the same size (or at least, only as much as the smallest device
 	  will be used).
 	  RAID-10 provides a variety of layouts that provide different levels
 	  of redundancy and performance.

 	  RAID-10 requires mdadm-1.7.0 or later, available at:

 	  ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/

 	  If unsure, say Y.

 config MD_RAID456
 	tristate "RAID-4/RAID-5/RAID-6 mode"
 	depends on BLK_DEV_MD
 	select ASYNC_MEMCPY
 	select ASYNC_XOR
 	---help---
 	  A RAID-5 set of N drives with a capacity of C MB per drive provides
 	  the capacity of C * (N - 1) MB, and protects against a failure
 	  of a single drive. For a given sector (row) number, (N - 1) drives
 	  contain data sectors, and one drive contains the parity protection.
 	  For a RAID-4 set, the parity blocks are present on a single drive,
 	  while a RAID-5 set distributes the parity across the drives in one
 	  of the available parity distribution methods.

 	  A RAID-6 set of N drives with a capacity of C MB per drive
 	  provides the capacity of C * (N - 2) MB, and protects
 	  against a failure of any two drives. For a given sector
 	  (row) number, (N - 2) drives contain data sectors, and two
 	  drives contains two independent redundancy syndromes.  Like
 	  RAID-5, RAID-6 distributes the syndromes across the drives
 	  in one of the available parity distribution methods.

 	  Information about Software RAID on Linux is contained in the
 	  Software-RAID mini-HOWTO, available from
 	  <http://www.tldp.org/docs.html#howto>. There you will also
 	  learn where to get the supporting user space utilities raidtools.

 	  If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y.  To
 	  compile this code as a module, choose M here: the module
 	  will be called raid456.

 	  If unsure, say Y.

 config MD_RAID5_RESHAPE
 	bool "Support adding drives to a raid-5 array"
 	depends on MD_RAID456
 	default y
 	---help---
 	  A RAID-5 set can be expanded by adding extra drives. This
 	  requires "restriping" the array which means (almost) every
 	  block must be written to a different place.

           This option allows such restriping to be done while the array
 	  is online.

 	  You will need mdadm version 2.4.1 or later to use this
 	  feature safely.  During the early stage of reshape there is
 	  a critical section where live data is being over-written.  A
 	  crash during this time needs extra care for recovery.  The
 	  newer mdadm takes a copy of the data in the critical section
 	  and will restore it, if necessary, after a crash.

 	  The mdadm usage is e.g.
 	       mdadm --grow /dev/md1 --raid-disks=6
 	  to grow '/dev/md1' to having 6 disks.

 	  Note: The array can only be expanded, not contracted.
 	  There should be enough spares already present to make the new
 	  array workable.

 	  If unsure, say Y.

 config MD_MULTIPATH
 	tristate "Multipath I/O support"
 	depends on BLK_DEV_MD
 	help
 	  Multipath-IO is the ability of certain devices to address the same
 	  physical disk over multiple 'IO paths'. The code ensures that such
 	  paths can be defined and handled at runtime, and ensures that a
 	  transparent failover to the backup path(s) happens if a IO errors
 	  arrives on the primary path.

 	  If unsure, say N.

 config MD_FAULTY
 	tristate "Faulty test module for MD"
 	depends on BLK_DEV_MD
 	help
 	  The "faulty" module allows for a block device that occasionally returns
 	  read or write errors.  It is useful for testing.

 	  In unsure, say N.

 config BLK_DEV_DM
 	tristate "Device mapper support"
 	---help---
 	  Device-mapper is a low level volume manager.  It works by allowing
 	  people to specify mappings for ranges of logical sectors.  Various
 	  mapping types are available, in addition people may write their own
 	  modules containing custom mappings if they wish.

 	  Higher level volume managers such as LVM2 use this driver.

 	  To compile this as a module, choose M here: the module will be
 	  called dm-mod.

 	  If unsure, say N.

 config DM_DEBUG
 	boolean "Device mapper debugging support"
 	depends on BLK_DEV_DM
 	---help---
 	  Enable this for messages that may help debug device-mapper problems.

 	  If unsure, say N.

 config DM_CRYPT
 	tristate "Crypt target support"
 	depends on BLK_DEV_DM
 	select CRYPTO
 	select CRYPTO_CBC
 	---help---
 	  This device-mapper target allows you to create a device that
 	  transparently encrypts the data on it. You'll need to activate
 	  the ciphers you're going to use in the cryptoapi configuration.

 	  Information on how to use dm-crypt can be found on

 	  <http://www.saout.de/misc/dm-crypt/>

 	  To compile this code as a module, choose M here: the module will
 	  be called dm-crypt.

 	  If unsure, say N.

 config DM_SNAPSHOT
        tristate "Snapshot target"
        depends on BLK_DEV_DM
        ---help---
          Allow volume managers to take writable snapshots of a device.

 config DM_MIRROR
        tristate "Mirror target"
        depends on BLK_DEV_DM
        ---help---
          Allow volume managers to mirror logical volumes, also
          needed for live data migration tools such as 'pvmove'.

 config DM_ZERO
 	tristate "Zero target"
 	depends on BLK_DEV_DM
 	---help---
 	  A target that discards writes, and returns all zeroes for
 	  reads.  Useful in some recovery situations.

 config DM_MULTIPATH
 	tristate "Multipath target"
 	depends on BLK_DEV_DM
 	# nasty syntax but means make DM_MULTIPATH independent
 	# of SCSI_DH if the latter isn't defined but if
 	# it is, DM_MULTIPATH must depend on it.  We get a build
 	# error if SCSI_DH=m and DM_MULTIPATH=y
 	depends on SCSI_DH || !SCSI_DH
 	---help---
 	  Allow volume managers to support multipath hardware.

 config DM_DELAY
 	tristate "I/O delaying target (EXPERIMENTAL)"
 	depends on BLK_DEV_DM && EXPERIMENTAL
 	---help---
 	A target that delays reads and/or writes and can send
 	them to different devices.  Useful for testing.

 	If unsure, say N.

 config DM_UEVENT
 	bool "DM uevents (EXPERIMENTAL)"
 	depends on BLK_DEV_DM && EXPERIMENTAL
 	---help---
 	Generate udev events for DM events.

 endif # MD
	#
	# Block device driver configuration
	#

	menuconfig MD
	bool "Multiple devices driver support (RAID and LVM)"
	depends on BLOCK
	help
	Support multiple physical spindles through a single logical device.
	Required for RAID and logical volume management.

	if MD

	config BLK_DEV_MD
	tristate "RAID support"
	---help---
	This driver lets you combine several hard disk partitions into one
	logical block device. This can be used to simply append one
	partition to another one or to combine several redundant hard disks
	into a RAID1/4/5 device so as to provide protection against hard
	disk failures. This is called "Software RAID" since the combining of
	the partitions is done by the kernel. "Hardware RAID" means that the
	combining is done by a dedicated controller; if you have such a
	controller, you do not need to say Y here.

	More information about Software RAID on Linux is contained in the
	Software RAID mini-HOWTO, available from
	<http://www.tldp.org/docs.html#howto>. There you will also learn
	where to get the supporting user space utilities raidtools.

	If unsure, say N.

	config MD_AUTODETECT
	bool "Autodetect RAID arrays during kernel boot"
	depends on BLK_DEV_MD=y
	default y
	---help---
	If you say Y here, then the kernel will try to autodetect raid
	arrays as part of its boot process.

	If you don't use raid and say Y, this autodetection can cause
	a several-second delay in the boot time due to various
	synchronisation steps that are part of this step.

	If unsure, say Y.

	config MD_LINEAR
	tristate "Linear (append) mode"
	depends on BLK_DEV_MD
	---help---
	If you say Y here, then your multiple devices driver will be able to
	use the so-called linear mode, i.e. it will combine the hard disk
	partitions by simply appending one to the other.

	To compile this as a module, choose M here: the module
	will be called linear.

	If unsure, say Y.

	config MD_RAID0
	tristate "RAID-0 (striping) mode"
	depends on BLK_DEV_MD
	---help---
	If you say Y here, then your multiple devices driver will be able to
	use the so-called raid0 mode, i.e. it will combine the hard disk
	partitions into one logical device in such a fashion as to fill them
	up evenly, one chunk here and one chunk there. This will increase
	the throughput rate if the partitions reside on distinct disks.

	Information about Software RAID on Linux is contained in the
	Software-RAID mini-HOWTO, available from
	<http://www.tldp.org/docs.html#howto>. There you will also
	learn where to get the supporting user space utilities raidtools.

	To compile this as a module, choose M here: the module
	will be called raid0.

	If unsure, say Y.

	config MD_RAID1
	tristate "RAID-1 (mirroring) mode"
	depends on BLK_DEV_MD
	---help---
	A RAID-1 set consists of several disk drives which are exact copies
	of each other. In the event of a mirror failure, the RAID driver
	will continue to use the operational mirrors in the set, providing
	an error free MD (multiple device) to the higher levels of the
	kernel. In a set with N drives, the available space is the capacity
	of a single drive, and the set protects against a failure of (N - 1)
	drives.

	Information about Software RAID on Linux is contained in the
	Software-RAID mini-HOWTO, available from
	<http://www.tldp.org/docs.html#howto>. There you will also
	learn where to get the supporting user space utilities raidtools.

	If you want to use such a RAID-1 set, say Y. To compile this code
	as a module, choose M here: the module will be called raid1.

	If unsure, say Y.

	config MD_RAID10
	tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
	depends on BLK_DEV_MD && EXPERIMENTAL
	---help---
	RAID-10 provides a combination of striping (RAID-0) and
	mirroring (RAID-1) with easier configuration and more flexible
	layout.
	Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
	be the same size (or at least, only as much as the smallest device
	will be used).
	RAID-10 provides a variety of layouts that provide different levels
	of redundancy and performance.

	RAID-10 requires mdadm-1.7.0 or later, available at:

	ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/

	If unsure, say Y.

	config MD_RAID456
	tristate "RAID-4/RAID-5/RAID-6 mode"
	depends on BLK_DEV_MD
	select ASYNC_MEMCPY
	select ASYNC_XOR
	---help---
	A RAID-5 set of N drives with a capacity of C MB per drive provides
	the capacity of C * (N - 1) MB, and protects against a failure
	of a single drive. For a given sector (row) number, (N - 1) drives
	contain data sectors, and one drive contains the parity protection.
	For a RAID-4 set, the parity blocks are present on a single drive,
	while a RAID-5 set distributes the parity across the drives in one
	of the available parity distribution methods.

	A RAID-6 set of N drives with a capacity of C MB per drive
	provides the capacity of C * (N - 2) MB, and protects
	against a failure of any two drives. For a given sector
	(row) number, (N - 2) drives contain data sectors, and two
	drives contains two independent redundancy syndromes. Like
	RAID-5, RAID-6 distributes the syndromes across the drives
	in one of the available parity distribution methods.

	Information about Software RAID on Linux is contained in the
	Software-RAID mini-HOWTO, available from
	<http://www.tldp.org/docs.html#howto>. There you will also
	learn where to get the supporting user space utilities raidtools.

	If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
	compile this code as a module, choose M here: the module
	will be called raid456.

	If unsure, say Y.

	config MD_RAID5_RESHAPE
	bool "Support adding drives to a raid-5 array"
	depends on MD_RAID456
	default y
	---help---
	A RAID-5 set can be expanded by adding extra drives. This
	requires "restriping" the array which means (almost) every
	block must be written to a different place.

	This option allows such restriping to be done while the array
	is online.

	You will need mdadm version 2.4.1 or later to use this
	feature safely. During the early stage of reshape there is
	a critical section where live data is being over-written. A
	crash during this time needs extra care for recovery. The
	newer mdadm takes a copy of the data in the critical section
	and will restore it, if necessary, after a crash.

	The mdadm usage is e.g.
	mdadm --grow /dev/md1 --raid-disks=6
	to grow '/dev/md1' to having 6 disks.

	Note: The array can only be expanded, not contracted.
	There should be enough spares already present to make the new
	array workable.

	If unsure, say Y.

	config MD_MULTIPATH
	tristate "Multipath I/O support"
	depends on BLK_DEV_MD
	help
	Multipath-IO is the ability of certain devices to address the same
	physical disk over multiple 'IO paths'. The code ensures that such
	paths can be defined and handled at runtime, and ensures that a
	transparent failover to the backup path(s) happens if a IO errors
	arrives on the primary path.

	If unsure, say N.

	config MD_FAULTY
	tristate "Faulty test module for MD"
	depends on BLK_DEV_MD
	help
	The "faulty" module allows for a block device that occasionally returns
	read or write errors. It is useful for testing.

	In unsure, say N.

	config BLK_DEV_DM
	tristate "Device mapper support"
	---help---
	Device-mapper is a low level volume manager. It works by allowing
	people to specify mappings for ranges of logical sectors. Various
	mapping types are available, in addition people may write their own
	modules containing custom mappings if they wish.

	Higher level volume managers such as LVM2 use this driver.

	To compile this as a module, choose M here: the module will be
	called dm-mod.

	If unsure, say N.

	config DM_DEBUG
	boolean "Device mapper debugging support"
	depends on BLK_DEV_DM
	---help---
	Enable this for messages that may help debug device-mapper problems.

	If unsure, say N.

	config DM_CRYPT
	tristate "Crypt target support"
	depends on BLK_DEV_DM
	select CRYPTO
	select CRYPTO_CBC
	---help---
	This device-mapper target allows you to create a device that
	transparently encrypts the data on it. You'll need to activate
	the ciphers you're going to use in the cryptoapi configuration.

	Information on how to use dm-crypt can be found on

	<http://www.saout.de/misc/dm-crypt/>

	To compile this code as a module, choose M here: the module will
	be called dm-crypt.

	If unsure, say N.

	config DM_SNAPSHOT
	tristate "Snapshot target"
	depends on BLK_DEV_DM
	---help---
	Allow volume managers to take writable snapshots of a device.

	config DM_MIRROR
	tristate "Mirror target"
	depends on BLK_DEV_DM
	---help---
	Allow volume managers to mirror logical volumes, also
	needed for live data migration tools such as 'pvmove'.

	config DM_ZERO
	tristate "Zero target"
	depends on BLK_DEV_DM
	---help---
	A target that discards writes, and returns all zeroes for
	reads. Useful in some recovery situations.

	config DM_MULTIPATH
	tristate "Multipath target"
	depends on BLK_DEV_DM
	# nasty syntax but means make DM_MULTIPATH independent
	# of SCSI_DH if the latter isn't defined but if
	# it is, DM_MULTIPATH must depend on it. We get a build
	# error if SCSI_DH=m and DM_MULTIPATH=y
	depends on SCSI_DH \|\| !SCSI_DH
	---help---
	Allow volume managers to support multipath hardware.

	config DM_DELAY
	tristate "I/O delaying target (EXPERIMENTAL)"
	depends on BLK_DEV_DM && EXPERIMENTAL
	---help---
	A target that delays reads and/or writes and can send
	them to different devices. Useful for testing.

	If unsure, say N.

	config DM_UEVENT
	bool "DM uevents (EXPERIMENTAL)"
	depends on BLK_DEV_DM && EXPERIMENTAL
	---help---
	Generate udev events for DM events.

	endif # MD