[linux.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
	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
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
	34	bool "Autodetect RAID arrays during kernel boot"
	35	depends on BLK_DEV_MD
	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
	103	tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
	104	depends on BLK_DEV_MD && EXPERIMENTAL
	105	---help---
	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
9bc89cd8 DW	124	select ASYNC_MEMCPY
9bc89cd8 DW	125	select ASYNC_XOR
1da177e4 LT	126	---help---
	127	A RAID-5 set of N drives with a capacity of C MB per drive provides
	128	the capacity of C * (N - 1) MB, and protects against a failure
	129	of a single drive. For a given sector (row) number, (N - 1) drives
	130	contain data sectors, and one drive contains the parity protection.
	131	For a RAID-4 set, the parity blocks are present on a single drive,
	132	while a RAID-5 set distributes the parity across the drives in one
	133	of the available parity distribution methods.
	134
16a53ecc N	135	A RAID-6 set of N drives with a capacity of C MB per drive
	136	provides the capacity of C * (N - 2) MB, and protects
	137	against a failure of any two drives. For a given sector
	138	(row) number, (N - 2) drives contain data sectors, and two
	139	drives contains two independent redundancy syndromes. Like
	140	RAID-5, RAID-6 distributes the syndromes across the drives
	141	in one of the available parity distribution methods.
	142
1da177e4 LT	143	Information about Software RAID on Linux is contained in the
	144	Software-RAID mini-HOWTO, available from
	145	<http://www.tldp.org/docs.html#howto>. There you will also
	146	learn where to get the supporting user space utilities raidtools.
	147
16a53ecc	148	If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
1da177e4	149	compile this code as a module, choose M here: the module
16a53ecc	150	will be called raid456.
1da177e4 LT	151
	152	If unsure, say Y.
	153
29269553	154	config MD_RAID5_RESHAPE
14f50b49 N	155	bool "Support adding drives to a raid-5 array"
	156	depends on MD_RAID456
	157	default y
29269553 N	158	---help---
	159	A RAID-5 set can be expanded by adding extra drives. This
	160	requires "restriping" the array which means (almost) every
	161	block must be written to a different place.
	162
	163	This option allows such restriping to be done while the array
14f50b49	164	is online.
29269553	165
4d2554d0	166	You will need mdadm version 2.4.1 or later to use this
6f91fe88 N	167	feature safely. During the early stage of reshape there is
	168	a critical section where live data is being over-written. A
	169	crash during this time needs extra care for recovery. The
	170	newer mdadm takes a copy of the data in the critical section
	171	and will restore it, if necessary, after a crash.
29269553 N	172
	173	The mdadm usage is e.g.
	174	mdadm --grow /dev/md1 --raid-disks=6
	175	to grow '/dev/md1' to having 6 disks.
	176
	177	Note: The array can only be expanded, not contracted.
	178	There should be enough spares already present to make the new
	179	array workable.
	180
14f50b49 N	181	If unsure, say Y.
14f50b49 N	182
1da177e4 LT	183	config MD_MULTIPATH
	184	tristate "Multipath I/O support"
	185	depends on BLK_DEV_MD
	186	help
	187	Multipath-IO is the ability of certain devices to address the same
	188	physical disk over multiple 'IO paths'. The code ensures that such
	189	paths can be defined and handled at runtime, and ensures that a
	190	transparent failover to the backup path(s) happens if a IO errors
	191	arrives on the primary path.
	192
	193	If unsure, say N.
	194
	195	config MD_FAULTY
	196	tristate "Faulty test module for MD"
	197	depends on BLK_DEV_MD
	198	help
	199	The "faulty" module allows for a block device that occasionally returns
	200	read or write errors. It is useful for testing.
	201
	202	In unsure, say N.
	203
	204	config BLK_DEV_DM
	205	tristate "Device mapper support"
1da177e4 LT	206	---help---
	207	Device-mapper is a low level volume manager. It works by allowing
	208	people to specify mappings for ranges of logical sectors. Various
	209	mapping types are available, in addition people may write their own
	210	modules containing custom mappings if they wish.
	211
	212	Higher level volume managers such as LVM2 use this driver.
	213
	214	To compile this as a module, choose M here: the module will be
	215	called dm-mod.
	216
	217	If unsure, say N.
	218
cc109201 BR	219	config DM_DEBUG
cc109201 BR	220	boolean "Device mapper debugging support"
0149e57f	221	depends on BLK_DEV_DM
cc109201 BR	222	---help---
	223	Enable this for messages that may help debug device-mapper problems.
	224
	225	If unsure, say N.
	226
1da177e4 LT	227	config DM_CRYPT
1da177e4 LT	228	tristate "Crypt target support"
0149e57f	229	depends on BLK_DEV_DM
1da177e4	230	select CRYPTO
3263263f	231	select CRYPTO_CBC
1da177e4 LT	232	---help---
	233	This device-mapper target allows you to create a device that
	234	transparently encrypts the data on it. You'll need to activate
	235	the ciphers you're going to use in the cryptoapi configuration.
	236
	237	Information on how to use dm-crypt can be found on
	238
	239	<http://www.saout.de/misc/dm-crypt/>
	240
	241	To compile this code as a module, choose M here: the module will
	242	be called dm-crypt.
	243
	244	If unsure, say N.
	245
	246	config DM_SNAPSHOT
0149e57f AK	247	tristate "Snapshot target"
0149e57f AK	248	depends on BLK_DEV_DM
1da177e4	249	---help---
4d2554d0	250	Allow volume managers to take writable snapshots of a device.
1da177e4 LT	251
1da177e4 LT	252	config DM_MIRROR
0149e57f AK	253	tristate "Mirror target"
0149e57f AK	254	depends on BLK_DEV_DM
1da177e4 LT	255	---help---
	256	Allow volume managers to mirror logical volumes, also
	257	needed for live data migration tools such as 'pvmove'.
	258
	259	config DM_ZERO
0149e57f AK	260	tristate "Zero target"
0149e57f AK	261	depends on BLK_DEV_DM
1da177e4 LT	262	---help---
	263	A target that discards writes, and returns all zeroes for
	264	reads. Useful in some recovery situations.
	265
	266	config DM_MULTIPATH
0149e57f AK	267	tristate "Multipath target"
0149e57f AK	268	depends on BLK_DEV_DM
fe9233fb CS	269	# nasty syntax but means make DM_MULTIPATH independent
	270	# of SCSI_DH if the latter isn't defined but if
	271	# it is, DM_MULTIPATH must depend on it. We get a build
	272	# error if SCSI_DH=m and DM_MULTIPATH=y
	273	depends on SCSI_DH \|\| !SCSI_DH
1da177e4 LT	274	---help---
	275	Allow volume managers to support multipath hardware.
	276
26b9f228 HM	277	config DM_DELAY
	278	tristate "I/O delaying target (EXPERIMENTAL)"
	279	depends on BLK_DEV_DM && EXPERIMENTAL
	280	---help---
	281	A target that delays reads and/or writes and can send
	282	them to different devices. Useful for testing.
	283
	284	If unsure, say N.
	285
51e5b2bd MA	286	config DM_UEVENT
	287	bool "DM uevents (EXPERIMENTAL)"
	288	depends on BLK_DEV_DM && EXPERIMENTAL
	289	---help---
	290	Generate udev events for DM events.
	291
afd44034	292	endif # MD