[linux.git] / drivers / md / Kconfig

#
# Block device driver configuration
#

menu "Multi-device support (RAID and LVM)"

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

config BLK_DEV_MD
	tristate "RAID support"
	depends on MD
	---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_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 flexable
	  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
	---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 (experimental)"
	depends on MD_RAID5 && EXPERIMENTAL
	---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.  However it is still EXPERIMENTAL code.  It should
	  work, but please be sure that you have backups.

	  You will need mdadm verion 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.

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"
	depends on MD
	---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_CRYPT
	tristate "Crypt target support"
	depends on BLK_DEV_DM && EXPERIMENTAL
	select CRYPTO
	---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 (EXPERIMENTAL)"
       depends on BLK_DEV_DM && EXPERIMENTAL
       ---help---
         Allow volume managers to take writeable snapshots of a device.

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

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

config DM_MULTIPATH
	tristate "Multipath target (EXPERIMENTAL)"
	depends on BLK_DEV_DM && EXPERIMENTAL
	---help---
	  Allow volume managers to support multipath hardware.

config DM_MULTIPATH_EMC
	tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
	depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
	---help---
	  Multipath support for EMC CX/AX series hardware.

endmenu
Commit	Line	Data
1da177e4 LT	1	#
	2	# Block device driver configuration
	3	#
	4
	5	menu "Multi-device support (RAID and LVM)"
	6
	7	config MD
	8	bool "Multiple devices driver support (RAID and LVM)"
	9	help
	10	Support multiple physical spindles through a single logical device.
	11	Required for RAID and logical volume management.
	12
	13	config BLK_DEV_MD
	14	tristate "RAID support"
	15	depends on MD
	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
	33	config MD_LINEAR
	34	tristate "Linear (append) mode"
	35	depends on BLK_DEV_MD
	36	---help---
	37	If you say Y here, then your multiple devices driver will be able to
	38	use the so-called linear mode, i.e. it will combine the hard disk
	39	partitions by simply appending one to the other.
	40
	41	To compile this as a module, choose M here: the module
	42	will be called linear.
	43
	44	If unsure, say Y.
	45
	46	config MD_RAID0
	47	tristate "RAID-0 (striping) mode"
	48	depends on BLK_DEV_MD
	49	---help---
	50	If you say Y here, then your multiple devices driver will be able to
	51	use the so-called raid0 mode, i.e. it will combine the hard disk
	52	partitions into one logical device in such a fashion as to fill them
	53	up evenly, one chunk here and one chunk there. This will increase
	54	the throughput rate if the partitions reside on distinct disks.
	55
	56	Information about Software RAID on Linux is contained in the
	57	Software-RAID mini-HOWTO, available from
	58	<http://www.tldp.org/docs.html#howto>. There you will also
	59	learn where to get the supporting user space utilities raidtools.
	60
	61	To compile this as a module, choose M here: the module
	62	will be called raid0.
	63
	64	If unsure, say Y.
65
66	config MD_RAID1
67	tristate "RAID-1 (mirroring) mode"
68	depends on BLK_DEV_MD
69	---help---
70	A RAID-1 set consists of several disk drives which are exact copies
71	of each other. In the event of a mirror failure, the RAID driver
72	will continue to use the operational mirrors in the set, providing
73	an error free MD (multiple device) to the higher levels of the
74	kernel. In a set with N drives, the available space is the capacity
75	of a single drive, and the set protects against a failure of (N - 1)
76	drives.
77
78	Information about Software RAID on Linux is contained in the
79	Software-RAID mini-HOWTO, available from
80	<http://www.tldp.org/docs.html#howto>. There you will also
81	learn where to get the supporting user space utilities raidtools.
82
83	If you want to use such a RAID-1 set, say Y. To compile this code
84	as a module, choose M here: the module will be called raid1.
85
86	If unsure, say Y.
87
88	config MD_RAID10
89	tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
90	depends on BLK_DEV_MD && EXPERIMENTAL
91	---help---
92	RAID-10 provides a combination of striping (RAID-0) and
93	mirroring (RAID-1) with easier configuration and more flexable
94	layout.
95	Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
96	be the same size (or at least, only as much as the smallest device
97	will be used).
98	RAID-10 provides a variety of layouts that provide different levels
99	of redundancy and performance.
100
101	RAID-10 requires mdadm-1.7.0 or later, available at:
102
103	ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
104
105	If unsure, say Y.
106
16a53ecc N	107	config MD_RAID456
16a53ecc N	108	tristate "RAID-4/RAID-5/RAID-6 mode"
1da177e4 LT	109	depends on BLK_DEV_MD
	110	---help---
	111	A RAID-5 set of N drives with a capacity of C MB per drive provides
	112	the capacity of C * (N - 1) MB, and protects against a failure
	113	of a single drive. For a given sector (row) number, (N - 1) drives
	114	contain data sectors, and one drive contains the parity protection.
	115	For a RAID-4 set, the parity blocks are present on a single drive,
	116	while a RAID-5 set distributes the parity across the drives in one
	117	of the available parity distribution methods.
	118
16a53ecc N	119	A RAID-6 set of N drives with a capacity of C MB per drive
	120	provides the capacity of C * (N - 2) MB, and protects
	121	against a failure of any two drives. For a given sector
	122	(row) number, (N - 2) drives contain data sectors, and two
	123	drives contains two independent redundancy syndromes. Like
	124	RAID-5, RAID-6 distributes the syndromes across the drives
	125	in one of the available parity distribution methods.
	126
1da177e4 LT	127	Information about Software RAID on Linux is contained in the
	128	Software-RAID mini-HOWTO, available from
	129	<http://www.tldp.org/docs.html#howto>. There you will also
	130	learn where to get the supporting user space utilities raidtools.
	131
16a53ecc	132	If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
1da177e4	133	compile this code as a module, choose M here: the module
16a53ecc	134	will be called raid456.
1da177e4 LT	135
	136	If unsure, say Y.
	137
29269553 N	138	config MD_RAID5_RESHAPE
	139	bool "Support adding drives to a raid-5 array (experimental)"
	140	depends on MD_RAID5 && EXPERIMENTAL
	141	---help---
	142	A RAID-5 set can be expanded by adding extra drives. This
	143	requires "restriping" the array which means (almost) every
	144	block must be written to a different place.
	145
	146	This option allows such restriping to be done while the array
	147	is online. However it is still EXPERIMENTAL code. It should
	148	work, but please be sure that you have backups.
	149
6f91fe88 N	150	You will need mdadm verion 2.4.1 or later to use this
	151	feature safely. During the early stage of reshape there is
	152	a critical section where live data is being over-written. A
	153	crash during this time needs extra care for recovery. The
	154	newer mdadm takes a copy of the data in the critical section
	155	and will restore it, if necessary, after a crash.
29269553 N	156
	157	The mdadm usage is e.g.
	158	mdadm --grow /dev/md1 --raid-disks=6
	159	to grow '/dev/md1' to having 6 disks.
	160
	161	Note: The array can only be expanded, not contracted.
	162	There should be enough spares already present to make the new
	163	array workable.
	164
1da177e4 LT	165	config MD_MULTIPATH
	166	tristate "Multipath I/O support"
	167	depends on BLK_DEV_MD
	168	help
	169	Multipath-IO is the ability of certain devices to address the same
	170	physical disk over multiple 'IO paths'. The code ensures that such
	171	paths can be defined and handled at runtime, and ensures that a
	172	transparent failover to the backup path(s) happens if a IO errors
	173	arrives on the primary path.
	174
	175	If unsure, say N.
	176
	177	config MD_FAULTY
	178	tristate "Faulty test module for MD"
	179	depends on BLK_DEV_MD
	180	help
	181	The "faulty" module allows for a block device that occasionally returns
	182	read or write errors. It is useful for testing.
	183
	184	In unsure, say N.
	185
	186	config BLK_DEV_DM
	187	tristate "Device mapper support"
	188	depends on MD
	189	---help---
	190	Device-mapper is a low level volume manager. It works by allowing
	191	people to specify mappings for ranges of logical sectors. Various
	192	mapping types are available, in addition people may write their own
	193	modules containing custom mappings if they wish.
	194
	195	Higher level volume managers such as LVM2 use this driver.
	196
	197	To compile this as a module, choose M here: the module will be
	198	called dm-mod.
	199
	200	If unsure, say N.
	201
	202	config DM_CRYPT
	203	tristate "Crypt target support"
	204	depends on BLK_DEV_DM && EXPERIMENTAL
	205	select CRYPTO
	206	---help---
	207	This device-mapper target allows you to create a device that
	208	transparently encrypts the data on it. You'll need to activate
	209	the ciphers you're going to use in the cryptoapi configuration.
	210
	211	Information on how to use dm-crypt can be found on
	212
	213	<http://www.saout.de/misc/dm-crypt/>
	214
	215	To compile this code as a module, choose M here: the module will
	216	be called dm-crypt.
	217
	218	If unsure, say N.
	219
	220	config DM_SNAPSHOT
	221	tristate "Snapshot target (EXPERIMENTAL)"
	222	depends on BLK_DEV_DM && EXPERIMENTAL
	223	---help---
	224	Allow volume managers to take writeable snapshots of a device.
	225
	226	config DM_MIRROR
	227	tristate "Mirror target (EXPERIMENTAL)"
	228	depends on BLK_DEV_DM && EXPERIMENTAL
229	---help---
230	Allow volume managers to mirror logical volumes, also
231	needed for live data migration tools such as 'pvmove'.
232
233	config DM_ZERO
234	tristate "Zero target (EXPERIMENTAL)"
235	depends on BLK_DEV_DM && EXPERIMENTAL
236	---help---
237	A target that discards writes, and returns all zeroes for
238	reads. Useful in some recovery situations.
239
240	config DM_MULTIPATH
241	tristate "Multipath target (EXPERIMENTAL)"
242	depends on BLK_DEV_DM && EXPERIMENTAL
243	---help---
244	Allow volume managers to support multipath hardware.
245
246	config DM_MULTIPATH_EMC
247	tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
248	depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
249	---help---
250	Multipath support for EMC CX/AX series hardware.
251
252	endmenu
253