[linux-block.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_RAID5
	tristate "RAID-4/RAID-5 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.

	  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 set, say Y.  To
	  compile this code as a module, choose M here: the module
	  will be called raid5.

	  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_RAID6
	tristate "RAID-6 mode"
	depends on BLK_DEV_MD
	---help---
	  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.

	  RAID-6 requires mdadm-1.5.0 or later, available at:

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

	  If you want to use such a RAID-6 set, say Y.  To compile
	  this code as a module, choose M here: the module will be
	  called raid6.

	  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"
	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
107	config MD_RAID5
108	tristate "RAID-4/RAID-5 mode"
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
119	Information about Software RAID on Linux is contained in the
120	Software-RAID mini-HOWTO, available from
121	<http://www.tldp.org/docs.html#howto>. There you will also
122	learn where to get the supporting user space utilities raidtools.
123
124	If you want to use such a RAID-4/RAID-5 set, say Y. To
125	compile this code as a module, choose M here: the module
126	will be called raid5.
127
128	If unsure, say Y.
129
29269553 N	130	config MD_RAID5_RESHAPE
	131	bool "Support adding drives to a raid-5 array (experimental)"
	132	depends on MD_RAID5 && EXPERIMENTAL
	133	---help---
	134	A RAID-5 set can be expanded by adding extra drives. This
	135	requires "restriping" the array which means (almost) every
	136	block must be written to a different place.
	137
	138	This option allows such restriping to be done while the array
	139	is online. However it is still EXPERIMENTAL code. It should
	140	work, but please be sure that you have backups.
	141
6f91fe88 N	142	You will need mdadm verion 2.4.1 or later to use this
	143	feature safely. During the early stage of reshape there is
	144	a critical section where live data is being over-written. A
	145	crash during this time needs extra care for recovery. The
	146	newer mdadm takes a copy of the data in the critical section
	147	and will restore it, if necessary, after a crash.
29269553 N	148
	149	The mdadm usage is e.g.
	150	mdadm --grow /dev/md1 --raid-disks=6
	151	to grow '/dev/md1' to having 6 disks.
	152
	153	Note: The array can only be expanded, not contracted.
	154	There should be enough spares already present to make the new
	155	array workable.
	156
1da177e4 LT	157	config MD_RAID6
	158	tristate "RAID-6 mode"
	159	depends on BLK_DEV_MD
	160	---help---
	161	A RAID-6 set of N drives with a capacity of C MB per drive
	162	provides the capacity of C * (N - 2) MB, and protects
	163	against a failure of any two drives. For a given sector
	164	(row) number, (N - 2) drives contain data sectors, and two
	165	drives contains two independent redundancy syndromes. Like
	166	RAID-5, RAID-6 distributes the syndromes across the drives
	167	in one of the available parity distribution methods.
	168
	169	RAID-6 requires mdadm-1.5.0 or later, available at:
	170
	171	ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
	172
	173	If you want to use such a RAID-6 set, say Y. To compile
	174	this code as a module, choose M here: the module will be
	175	called raid6.
	176
	177	If unsure, say Y.
	178
	179	config MD_MULTIPATH
	180	tristate "Multipath I/O support"
	181	depends on BLK_DEV_MD
	182	help
	183	Multipath-IO is the ability of certain devices to address the same
	184	physical disk over multiple 'IO paths'. The code ensures that such
	185	paths can be defined and handled at runtime, and ensures that a
	186	transparent failover to the backup path(s) happens if a IO errors
	187	arrives on the primary path.
	188
	189	If unsure, say N.
	190
	191	config MD_FAULTY
	192	tristate "Faulty test module for MD"
	193	depends on BLK_DEV_MD
	194	help
	195	The "faulty" module allows for a block device that occasionally returns
	196	read or write errors. It is useful for testing.
	197
	198	In unsure, say N.
	199
	200	config BLK_DEV_DM
	201	tristate "Device mapper support"
	202	depends on MD
	203	---help---
	204	Device-mapper is a low level volume manager. It works by allowing
	205	people to specify mappings for ranges of logical sectors. Various
	206	mapping types are available, in addition people may write their own
	207	modules containing custom mappings if they wish.
	208
	209	Higher level volume managers such as LVM2 use this driver.
	210
	211	To compile this as a module, choose M here: the module will be
	212	called dm-mod.
	213
	214	If unsure, say N.
	215
	216	config DM_CRYPT
	217	tristate "Crypt target support"
	218	depends on BLK_DEV_DM && EXPERIMENTAL
	219	select CRYPTO
	220	---help---
221	This device-mapper target allows you to create a device that
222	transparently encrypts the data on it. You'll need to activate
223	the ciphers you're going to use in the cryptoapi configuration.
224
225	Information on how to use dm-crypt can be found on
226
227	<http://www.saout.de/misc/dm-crypt/>
228
229	To compile this code as a module, choose M here: the module will
230	be called dm-crypt.
231
232	If unsure, say N.
233
234	config DM_SNAPSHOT
235	tristate "Snapshot target (EXPERIMENTAL)"
236	depends on BLK_DEV_DM && EXPERIMENTAL
237	---help---
238	Allow volume managers to take writeable snapshots of a device.
239
240	config DM_MIRROR
241	tristate "Mirror target (EXPERIMENTAL)"
242	depends on BLK_DEV_DM && EXPERIMENTAL
243	---help---
244	Allow volume managers to mirror logical volumes, also
245	needed for live data migration tools such as 'pvmove'.
246
247	config DM_ZERO
248	tristate "Zero target (EXPERIMENTAL)"
249	depends on BLK_DEV_DM && EXPERIMENTAL
250	---help---
251	A target that discards writes, and returns all zeroes for
252	reads. Useful in some recovery situations.
253
254	config DM_MULTIPATH
255	tristate "Multipath target (EXPERIMENTAL)"
256	depends on BLK_DEV_DM && EXPERIMENTAL
257	---help---
258	Allow volume managers to support multipath hardware.
259
260	config DM_MULTIPATH_EMC
261	tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
262	depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
263	---help---
264	Multipath support for EMC CX/AX series hardware.
265
266	endmenu
267