[linux-2.6-block.git] / drivers / md / Kconfig

#
# 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"
	depends on BLK_DEV_MD
	---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 RAID6_PQ
	select ASYNC_MEMCPY
	select ASYNC_XOR
	select ASYNC_PQ
	select ASYNC_RAID6_RECOV
	---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 MULTICORE_RAID456
	bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
	depends on MD_RAID456
	depends on SMP
	depends on EXPERIMENTAL
	---help---
	  Enable the raid456 module to dispatch per-stripe raid operations to a
	  thread pool.

	  If unsure, say N.

config MD_MULTIPATH
	tristate "Multipath I/O support"
	depends on BLK_DEV_MD
	help
	  MD_MULTIPATH provides a simple multi-path personality for use
	  the MD framework.  It is not under active development.  New
	  projects should consider using DM_MULTIPATH which has more
	  features and more testing.

	  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_BUFIO
       tristate
       depends on BLK_DEV_DM && EXPERIMENTAL
       ---help---
	 This interface allows you to do buffered I/O on a device and acts
	 as a cache, holding recently-read blocks in memory and performing
	 delayed writes.

source "drivers/md/persistent-data/Kconfig"

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_THIN_PROVISIONING
       tristate "Thin provisioning target (EXPERIMENTAL)"
       depends on BLK_DEV_DM && EXPERIMENTAL
       select DM_PERSISTENT_DATA
       ---help---
         Provides thin provisioning and snapshots that share a data store.

config DM_DEBUG_BLOCK_STACK_TRACING
	boolean "Keep stack trace of thin provisioning block lock holders"
	depends on STACKTRACE_SUPPORT && DM_THIN_PROVISIONING
	select STACKTRACE
	---help---
	  Enable this for messages that may help debug problems with the
	  block manager locking used by thin provisioning.

	  If unsure, say N.

config DM_DEBUG_SPACE_MAPS
	boolean "Extra validation for thin provisioning space maps"
	depends on DM_THIN_PROVISIONING
	---help---
	  Enable this for messages that may help debug problems with the
	  space maps used by thin provisioning.

          If unsure, say N.

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_RAID
       tristate "RAID 1/4/5/6 target"
       depends on BLK_DEV_DM
       select MD_RAID1
       select MD_RAID456
       select BLK_DEV_MD
       ---help---
	 A dm target that supports RAID1, RAID4, RAID5 and RAID6 mappings

	 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.

config DM_LOG_USERSPACE
	tristate "Mirror userspace logging (EXPERIMENTAL)"
	depends on DM_MIRROR && EXPERIMENTAL && NET
	select CONNECTOR
	---help---
	  The userspace logging module provides a mechanism for
	  relaying the dm-dirty-log API to userspace.  Log designs
	  which are more suited to userspace implementation (e.g.
	  shared storage logs) or experimental logs can be implemented
	  by leveraging this framework.

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_MULTIPATH_QL
	tristate "I/O Path Selector based on the number of in-flight I/Os"
	depends on DM_MULTIPATH
	---help---
	  This path selector is a dynamic load balancer which selects
	  the path with the least number of in-flight I/Os.

	  If unsure, say N.

config DM_MULTIPATH_ST
	tristate "I/O Path Selector based on the service time"
	depends on DM_MULTIPATH
	---help---
	  This path selector is a dynamic load balancer which selects
	  the path expected to complete the incoming I/O in the shortest
	  time.

	  If unsure, say N.

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"
	depends on BLK_DEV_DM
	---help---
	Generate udev events for DM events.

config DM_FLAKEY
       tristate "Flakey target (EXPERIMENTAL)"
       depends on BLK_DEV_DM && EXPERIMENTAL
       ---help---
         A target that intermittently fails I/O for debugging purposes.

config DM_VERITY
	tristate "Verity target support (EXPERIMENTAL)"
	depends on BLK_DEV_DM && EXPERIMENTAL
	select CRYPTO
	select CRYPTO_HASH
	select DM_BUFIO
	---help---
	  This device-mapper target creates a read-only device that
	  transparently validates the data on one underlying device against
	  a pre-generated tree of cryptographic checksums stored on a second
	  device.

	  You'll need to activate the digests you're going to use in the
	  cryptoapi configuration.

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

	  If unsure, say N.

endif # MD
Commit	Line	Data
1da177e4 LT	1	#
	2	# Block device driver configuration
	3	#
	4
afd44034	5	menuconfig MD
1da177e4	6	bool "Multiple devices driver support (RAID and LVM)"
afd44034	7	depends on BLOCK
1da177e4 LT	8	help
	9	Support multiple physical spindles through a single logical device.
	10	Required for RAID and logical volume management.
	11
afd44034 JE	12	if MD
afd44034 JE	13
1da177e4 LT	14	config BLK_DEV_MD
1da177e4 LT	15	tristate "RAID support"
1da177e4 LT	16	---help---
	17	This driver lets you combine several hard disk partitions into one
	18	logical block device. This can be used to simply append one
	19	partition to another one or to combine several redundant hard disks
	20	into a RAID1/4/5 device so as to provide protection against hard
	21	disk failures. This is called "Software RAID" since the combining of
	22	the partitions is done by the kernel. "Hardware RAID" means that the
	23	combining is done by a dedicated controller; if you have such a
	24	controller, you do not need to say Y here.
	25
	26	More information about Software RAID on Linux is contained in the
	27	Software RAID mini-HOWTO, available from
	28	<http://www.tldp.org/docs.html#howto>. There you will also learn
	29	where to get the supporting user space utilities raidtools.
	30
	31	If unsure, say N.
	32
a364092a AV	33	config MD_AUTODETECT
a364092a AV	34	bool "Autodetect RAID arrays during kernel boot"
ce52aebd	35	depends on BLK_DEV_MD=y
a364092a AV	36	default y
	37	---help---
	38	If you say Y here, then the kernel will try to autodetect raid
	39	arrays as part of its boot process.
	40
	41	If you don't use raid and say Y, this autodetection can cause
	42	a several-second delay in the boot time due to various
	43	synchronisation steps that are part of this step.
	44
	45	If unsure, say Y.
	46
1da177e4 LT	47	config MD_LINEAR
	48	tristate "Linear (append) mode"
	49	depends on BLK_DEV_MD
	50	---help---
	51	If you say Y here, then your multiple devices driver will be able to
	52	use the so-called linear mode, i.e. it will combine the hard disk
	53	partitions by simply appending one to the other.
	54
	55	To compile this as a module, choose M here: the module
	56	will be called linear.
	57
	58	If unsure, say Y.
	59
	60	config MD_RAID0
	61	tristate "RAID-0 (striping) mode"
	62	depends on BLK_DEV_MD
	63	---help---
	64	If you say Y here, then your multiple devices driver will be able to
	65	use the so-called raid0 mode, i.e. it will combine the hard disk
	66	partitions into one logical device in such a fashion as to fill them
	67	up evenly, one chunk here and one chunk there. This will increase
	68	the throughput rate if the partitions reside on distinct disks.
	69
	70	Information about Software RAID on Linux is contained in the
	71	Software-RAID mini-HOWTO, available from
	72	<http://www.tldp.org/docs.html#howto>. There you will also
	73	learn where to get the supporting user space utilities raidtools.
	74
	75	To compile this as a module, choose M here: the module
	76	will be called raid0.
	77
	78	If unsure, say Y.
	79
	80	config MD_RAID1
	81	tristate "RAID-1 (mirroring) mode"
	82	depends on BLK_DEV_MD
	83	---help---
	84	A RAID-1 set consists of several disk drives which are exact copies
	85	of each other. In the event of a mirror failure, the RAID driver
	86	will continue to use the operational mirrors in the set, providing
	87	an error free MD (multiple device) to the higher levels of the
	88	kernel. In a set with N drives, the available space is the capacity
	89	of a single drive, and the set protects against a failure of (N - 1)
	90	drives.
	91
	92	Information about Software RAID on Linux is contained in the
	93	Software-RAID mini-HOWTO, available from
	94	<http://www.tldp.org/docs.html#howto>. There you will also
	95	learn where to get the supporting user space utilities raidtools.
	96
	97	If you want to use such a RAID-1 set, say Y. To compile this code
	98	as a module, choose M here: the module will be called raid1.
	99
	100	If unsure, say Y.
	101
	102	config MD_RAID10
08fb730c N	103	tristate "RAID-10 (mirrored striping) mode"
08fb730c N	104	depends on BLK_DEV_MD
1da177e4 LT	105	---help---
1da177e4 LT	106	RAID-10 provides a combination of striping (RAID-0) and
4d2554d0	107	mirroring (RAID-1) with easier configuration and more flexible
1da177e4 LT	108	layout.
	109	Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
	110	be the same size (or at least, only as much as the smallest device
	111	will be used).
	112	RAID-10 provides a variety of layouts that provide different levels
	113	of redundancy and performance.
	114
	115	RAID-10 requires mdadm-1.7.0 or later, available at:
	116
	117	ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
	118
	119	If unsure, say Y.
	120
16a53ecc N	121	config MD_RAID456
16a53ecc N	122	tristate "RAID-4/RAID-5/RAID-6 mode"
1da177e4	123	depends on BLK_DEV_MD
f5e70d0f	124	select RAID6_PQ
9bc89cd8 DW	125	select ASYNC_MEMCPY
9bc89cd8 DW	126	select ASYNC_XOR
ac6b53b6 DW	127	select ASYNC_PQ
ac6b53b6 DW	128	select ASYNC_RAID6_RECOV
1da177e4 LT	129	---help---
	130	A RAID-5 set of N drives with a capacity of C MB per drive provides
	131	the capacity of C * (N - 1) MB, and protects against a failure
	132	of a single drive. For a given sector (row) number, (N - 1) drives
	133	contain data sectors, and one drive contains the parity protection.
	134	For a RAID-4 set, the parity blocks are present on a single drive,
	135	while a RAID-5 set distributes the parity across the drives in one
	136	of the available parity distribution methods.
	137
16a53ecc N	138	A RAID-6 set of N drives with a capacity of C MB per drive
	139	provides the capacity of C * (N - 2) MB, and protects
	140	against a failure of any two drives. For a given sector
	141	(row) number, (N - 2) drives contain data sectors, and two
	142	drives contains two independent redundancy syndromes. Like
	143	RAID-5, RAID-6 distributes the syndromes across the drives
	144	in one of the available parity distribution methods.
	145
1da177e4 LT	146	Information about Software RAID on Linux is contained in the
	147	Software-RAID mini-HOWTO, available from
	148	<http://www.tldp.org/docs.html#howto>. There you will also
	149	learn where to get the supporting user space utilities raidtools.
	150
16a53ecc	151	If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
1da177e4	152	compile this code as a module, choose M here: the module
16a53ecc	153	will be called raid456.
1da177e4 LT	154
	155	If unsure, say Y.
	156
07a3b417 DW	157	config MULTICORE_RAID456
	158	bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
	159	depends on MD_RAID456
	160	depends on SMP
	161	depends on EXPERIMENTAL
	162	---help---
	163	Enable the raid456 module to dispatch per-stripe raid operations to a
	164	thread pool.
	165
	166	If unsure, say N.
cb3c8299	167
1da177e4 LT	168	config MD_MULTIPATH
	169	tristate "Multipath I/O support"
	170	depends on BLK_DEV_MD
	171	help
93bd89a6 N	172	MD_MULTIPATH provides a simple multi-path personality for use
	173	the MD framework. It is not under active development. New
	174	projects should consider using DM_MULTIPATH which has more
	175	features and more testing.
1da177e4 LT	176
	177	If unsure, say N.
	178
	179	config MD_FAULTY
	180	tristate "Faulty test module for MD"
	181	depends on BLK_DEV_MD
	182	help
	183	The "faulty" module allows for a block device that occasionally returns
	184	read or write errors. It is useful for testing.
	185
	186	In unsure, say N.
	187
	188	config BLK_DEV_DM
	189	tristate "Device mapper support"
1da177e4 LT	190	---help---
	191	Device-mapper is a low level volume manager. It works by allowing
	192	people to specify mappings for ranges of logical sectors. Various
	193	mapping types are available, in addition people may write their own
	194	modules containing custom mappings if they wish.
	195
	196	Higher level volume managers such as LVM2 use this driver.
	197
	198	To compile this as a module, choose M here: the module will be
	199	called dm-mod.
	200
	201	If unsure, say N.
	202
cc109201 BR	203	config DM_DEBUG
cc109201 BR	204	boolean "Device mapper debugging support"
0149e57f	205	depends on BLK_DEV_DM
cc109201 BR	206	---help---
	207	Enable this for messages that may help debug device-mapper problems.
	208
	209	If unsure, say N.
	210
95d402f0 MP	211	config DM_BUFIO
	212	tristate
	213	depends on BLK_DEV_DM && EXPERIMENTAL
	214	---help---
	215	This interface allows you to do buffered I/O on a device and acts
	216	as a cache, holding recently-read blocks in memory and performing
	217	delayed writes.
	218
991d9fa0 JT	219	source "drivers/md/persistent-data/Kconfig"
991d9fa0 JT	220
1da177e4 LT	221	config DM_CRYPT
1da177e4 LT	222	tristate "Crypt target support"
0149e57f	223	depends on BLK_DEV_DM
1da177e4	224	select CRYPTO
3263263f	225	select CRYPTO_CBC
1da177e4 LT	226	---help---
	227	This device-mapper target allows you to create a device that
	228	transparently encrypts the data on it. You'll need to activate
	229	the ciphers you're going to use in the cryptoapi configuration.
	230
	231	Information on how to use dm-crypt can be found on
	232
	233	<http://www.saout.de/misc/dm-crypt/>
	234
	235	To compile this code as a module, choose M here: the module will
	236	be called dm-crypt.
	237
	238	If unsure, say N.
	239
	240	config DM_SNAPSHOT
0149e57f AK	241	tristate "Snapshot target"
0149e57f AK	242	depends on BLK_DEV_DM
1da177e4	243	---help---
4d2554d0	244	Allow volume managers to take writable snapshots of a device.
1da177e4	245
991d9fa0 JT	246	config DM_THIN_PROVISIONING
	247	tristate "Thin provisioning target (EXPERIMENTAL)"
	248	depends on BLK_DEV_DM && EXPERIMENTAL
	249	select DM_PERSISTENT_DATA
	250	---help---
	251	Provides thin provisioning and snapshots that share a data store.
	252
	253	config DM_DEBUG_BLOCK_STACK_TRACING
	254	boolean "Keep stack trace of thin provisioning block lock holders"
	255	depends on STACKTRACE_SUPPORT && DM_THIN_PROVISIONING
	256	select STACKTRACE
	257	---help---
	258	Enable this for messages that may help debug problems with the
	259	block manager locking used by thin provisioning.
	260
	261	If unsure, say N.
	262
	263	config DM_DEBUG_SPACE_MAPS
	264	boolean "Extra validation for thin provisioning space maps"
	265	depends on DM_THIN_PROVISIONING
	266	---help---
	267	Enable this for messages that may help debug problems with the
	268	space maps used by thin provisioning.
	269
	270	If unsure, say N.
	271
1da177e4	272	config DM_MIRROR
0149e57f AK	273	tristate "Mirror target"
0149e57f AK	274	depends on BLK_DEV_DM
1da177e4 LT	275	---help---
	276	Allow volume managers to mirror logical volumes, also
	277	needed for live data migration tools such as 'pvmove'.
	278
9d09e663	279	config DM_RAID
035220b3 AK	280	tristate "RAID 1/4/5/6 target"
035220b3 AK	281	depends on BLK_DEV_DM
b12d437b	282	select MD_RAID1
9d09e663 N	283	select MD_RAID456
	284	select BLK_DEV_MD
	285	---help---
b12d437b	286	A dm target that supports RAID1, RAID4, RAID5 and RAID6 mappings
9d09e663 N	287
	288	A RAID-5 set of N drives with a capacity of C MB per drive provides
	289	the capacity of C * (N - 1) MB, and protects against a failure
	290	of a single drive. For a given sector (row) number, (N - 1) drives
	291	contain data sectors, and one drive contains the parity protection.
	292	For a RAID-4 set, the parity blocks are present on a single drive,
	293	while a RAID-5 set distributes the parity across the drives in one
	294	of the available parity distribution methods.
	295
	296	A RAID-6 set of N drives with a capacity of C MB per drive
	297	provides the capacity of C * (N - 2) MB, and protects
	298	against a failure of any two drives. For a given sector
	299	(row) number, (N - 2) drives contain data sectors, and two
	300	drives contains two independent redundancy syndromes. Like
	301	RAID-5, RAID-6 distributes the syndromes across the drives
	302	in one of the available parity distribution methods.
	303
f5db4af4 JB	304	config DM_LOG_USERSPACE
	305	tristate "Mirror userspace logging (EXPERIMENTAL)"
	306	depends on DM_MIRROR && EXPERIMENTAL && NET
	307	select CONNECTOR
	308	---help---
	309	The userspace logging module provides a mechanism for
	310	relaying the dm-dirty-log API to userspace. Log designs
	311	which are more suited to userspace implementation (e.g.
	312	shared storage logs) or experimental logs can be implemented
	313	by leveraging this framework.
	314
1da177e4	315	config DM_ZERO
0149e57f AK	316	tristate "Zero target"
0149e57f AK	317	depends on BLK_DEV_DM
1da177e4 LT	318	---help---
	319	A target that discards writes, and returns all zeroes for
	320	reads. Useful in some recovery situations.
	321
	322	config DM_MULTIPATH
0149e57f AK	323	tristate "Multipath target"
0149e57f AK	324	depends on BLK_DEV_DM
fe9233fb CS	325	# nasty syntax but means make DM_MULTIPATH independent
	326	# of SCSI_DH if the latter isn't defined but if
	327	# it is, DM_MULTIPATH must depend on it. We get a build
	328	# error if SCSI_DH=m and DM_MULTIPATH=y
	329	depends on SCSI_DH \|\| !SCSI_DH
1da177e4 LT	330	---help---
	331	Allow volume managers to support multipath hardware.
	332
fd5e0339 KU	333	config DM_MULTIPATH_QL
	334	tristate "I/O Path Selector based on the number of in-flight I/Os"
	335	depends on DM_MULTIPATH
	336	---help---
	337	This path selector is a dynamic load balancer which selects
	338	the path with the least number of in-flight I/Os.
	339
	340	If unsure, say N.
	341
f392ba88 KU	342	config DM_MULTIPATH_ST
	343	tristate "I/O Path Selector based on the service time"
	344	depends on DM_MULTIPATH
	345	---help---
	346	This path selector is a dynamic load balancer which selects
	347	the path expected to complete the incoming I/O in the shortest
	348	time.
	349
	350	If unsure, say N.
	351
26b9f228 HM	352	config DM_DELAY
	353	tristate "I/O delaying target (EXPERIMENTAL)"
	354	depends on BLK_DEV_DM && EXPERIMENTAL
	355	---help---
	356	A target that delays reads and/or writes and can send
	357	them to different devices. Useful for testing.
	358
	359	If unsure, say N.
	360
51e5b2bd	361	config DM_UEVENT
e0b215da AK	362	bool "DM uevents"
e0b215da AK	363	depends on BLK_DEV_DM
51e5b2bd MA	364	---help---
	365	Generate udev events for DM events.
	366
3407ef52 JB	367	config DM_FLAKEY
	368	tristate "Flakey target (EXPERIMENTAL)"
	369	depends on BLK_DEV_DM && EXPERIMENTAL
	370	---help---
	371	A target that intermittently fails I/O for debugging purposes.
	372
a4ffc152 MP	373	config DM_VERITY
	374	tristate "Verity target support (EXPERIMENTAL)"
	375	depends on BLK_DEV_DM && EXPERIMENTAL
	376	select CRYPTO
	377	select CRYPTO_HASH
	378	select DM_BUFIO
	379	---help---
	380	This device-mapper target creates a read-only device that
	381	transparently validates the data on one underlying device against
	382	a pre-generated tree of cryptographic checksums stored on a second
	383	device.
	384
	385	You'll need to activate the digests you're going to use in the
	386	cryptoapi configuration.
	387
	388	To compile this code as a module, choose M here: the module will
	389	be called dm-verity.
	390
	391	If unsure, say N.
	392
afd44034	393	endif # MD