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

#
# Block device driver configuration
#

if BLOCK

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 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
	---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_RAID456 && 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 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.

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 writable 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

endif
Commit	Line	Data
1da177e4 LT	1	#
	2	# Block device driver configuration
	3	#
	4
9361401e DH	5	if BLOCK
9361401e DH	6
1da177e4 LT	7	menu "Multi-device support (RAID and LVM)"
	8
	9	config MD
	10	bool "Multiple devices driver support (RAID and LVM)"
	11	help
	12	Support multiple physical spindles through a single logical device.
	13	Required for RAID and logical volume management.
	14
	15	config BLK_DEV_MD
	16	tristate "RAID support"
	17	depends on MD
	18	---help---
	19	This driver lets you combine several hard disk partitions into one
	20	logical block device. This can be used to simply append one
	21	partition to another one or to combine several redundant hard disks
	22	into a RAID1/4/5 device so as to provide protection against hard
	23	disk failures. This is called "Software RAID" since the combining of
	24	the partitions is done by the kernel. "Hardware RAID" means that the
	25	combining is done by a dedicated controller; if you have such a
	26	controller, you do not need to say Y here.
	27
	28	More information about Software RAID on Linux is contained in the
	29	Software RAID mini-HOWTO, available from
	30	<http://www.tldp.org/docs.html#howto>. There you will also learn
	31	where to get the supporting user space utilities raidtools.
	32
	33	If unsure, say N.
	34
	35	config MD_LINEAR
	36	tristate "Linear (append) mode"
	37	depends on BLK_DEV_MD
	38	---help---
	39	If you say Y here, then your multiple devices driver will be able to
	40	use the so-called linear mode, i.e. it will combine the hard disk
	41	partitions by simply appending one to the other.
	42
	43	To compile this as a module, choose M here: the module
	44	will be called linear.
	45
	46	If unsure, say Y.
	47
	48	config MD_RAID0
	49	tristate "RAID-0 (striping) mode"
	50	depends on BLK_DEV_MD
	51	---help---
	52	If you say Y here, then your multiple devices driver will be able to
	53	use the so-called raid0 mode, i.e. it will combine the hard disk
	54	partitions into one logical device in such a fashion as to fill them
	55	up evenly, one chunk here and one chunk there. This will increase
	56	the throughput rate if the partitions reside on distinct disks.
	57
	58	Information about Software RAID on Linux is contained in the
	59	Software-RAID mini-HOWTO, available from
	60	<http://www.tldp.org/docs.html#howto>. There you will also
	61	learn where to get the supporting user space utilities raidtools.
	62
	63	To compile this as a module, choose M here: the module
	64	will be called raid0.
	65
	66	If unsure, say Y.
	67
	68	config MD_RAID1
	69	tristate "RAID-1 (mirroring) mode"
	70	depends on BLK_DEV_MD
71	---help---
72	A RAID-1 set consists of several disk drives which are exact copies
73	of each other. In the event of a mirror failure, the RAID driver
74	will continue to use the operational mirrors in the set, providing
75	an error free MD (multiple device) to the higher levels of the
76	kernel. In a set with N drives, the available space is the capacity
77	of a single drive, and the set protects against a failure of (N - 1)
78	drives.
79
80	Information about Software RAID on Linux is contained in the
81	Software-RAID mini-HOWTO, available from
82	<http://www.tldp.org/docs.html#howto>. There you will also
83	learn where to get the supporting user space utilities raidtools.
84
85	If you want to use such a RAID-1 set, say Y. To compile this code
86	as a module, choose M here: the module will be called raid1.
87
88	If unsure, say Y.
89
90	config MD_RAID10
91	tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
92	depends on BLK_DEV_MD && EXPERIMENTAL
93	---help---
94	RAID-10 provides a combination of striping (RAID-0) and
4d2554d0	95	mirroring (RAID-1) with easier configuration and more flexible
1da177e4 LT	96	layout.
	97	Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
	98	be the same size (or at least, only as much as the smallest device
	99	will be used).
	100	RAID-10 provides a variety of layouts that provide different levels
	101	of redundancy and performance.
	102
	103	RAID-10 requires mdadm-1.7.0 or later, available at:
	104
	105	ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
	106
	107	If unsure, say Y.
	108
16a53ecc N	109	config MD_RAID456
16a53ecc N	110	tristate "RAID-4/RAID-5/RAID-6 mode"
1da177e4 LT	111	depends on BLK_DEV_MD
	112	---help---
	113	A RAID-5 set of N drives with a capacity of C MB per drive provides
	114	the capacity of C * (N - 1) MB, and protects against a failure
	115	of a single drive. For a given sector (row) number, (N - 1) drives
	116	contain data sectors, and one drive contains the parity protection.
	117	For a RAID-4 set, the parity blocks are present on a single drive,
	118	while a RAID-5 set distributes the parity across the drives in one
	119	of the available parity distribution methods.
	120
16a53ecc N	121	A RAID-6 set of N drives with a capacity of C MB per drive
	122	provides the capacity of C * (N - 2) MB, and protects
	123	against a failure of any two drives. For a given sector
	124	(row) number, (N - 2) drives contain data sectors, and two
	125	drives contains two independent redundancy syndromes. Like
	126	RAID-5, RAID-6 distributes the syndromes across the drives
	127	in one of the available parity distribution methods.
	128
1da177e4 LT	129	Information about Software RAID on Linux is contained in the
	130	Software-RAID mini-HOWTO, available from
	131	<http://www.tldp.org/docs.html#howto>. There you will also
	132	learn where to get the supporting user space utilities raidtools.
	133
16a53ecc	134	If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
1da177e4	135	compile this code as a module, choose M here: the module
16a53ecc	136	will be called raid456.
1da177e4 LT	137
	138	If unsure, say Y.
	139
29269553 N	140	config MD_RAID5_RESHAPE
29269553 N	141	bool "Support adding drives to a raid-5 array (experimental)"
b3cc9ec7	142	depends on MD_RAID456 && EXPERIMENTAL
29269553 N	143	---help---
	144	A RAID-5 set can be expanded by adding extra drives. This
	145	requires "restriping" the array which means (almost) every
	146	block must be written to a different place.
	147
	148	This option allows such restriping to be done while the array
	149	is online. However it is still EXPERIMENTAL code. It should
	150	work, but please be sure that you have backups.
	151
4d2554d0	152	You will need mdadm version 2.4.1 or later to use this
6f91fe88 N	153	feature safely. During the early stage of reshape there is
	154	a critical section where live data is being over-written. A
	155	crash during this time needs extra care for recovery. The
	156	newer mdadm takes a copy of the data in the critical section
	157	and will restore it, if necessary, after a crash.
29269553 N	158
	159	The mdadm usage is e.g.
	160	mdadm --grow /dev/md1 --raid-disks=6
	161	to grow '/dev/md1' to having 6 disks.
	162
	163	Note: The array can only be expanded, not contracted.
	164	There should be enough spares already present to make the new
	165	array workable.
	166
1da177e4 LT	167	config MD_MULTIPATH
	168	tristate "Multipath I/O support"
	169	depends on BLK_DEV_MD
	170	help
	171	Multipath-IO is the ability of certain devices to address the same
	172	physical disk over multiple 'IO paths'. The code ensures that such
	173	paths can be defined and handled at runtime, and ensures that a
	174	transparent failover to the backup path(s) happens if a IO errors
	175	arrives on the primary path.
	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"
	190	depends on MD
	191	---help---
	192	Device-mapper is a low level volume manager. It works by allowing
	193	people to specify mappings for ranges of logical sectors. Various
	194	mapping types are available, in addition people may write their own
	195	modules containing custom mappings if they wish.
	196
	197	Higher level volume managers such as LVM2 use this driver.
	198
	199	To compile this as a module, choose M here: the module will be
	200	called dm-mod.
	201
	202	If unsure, say N.
	203
	204	config DM_CRYPT
	205	tristate "Crypt target support"
	206	depends on BLK_DEV_DM && EXPERIMENTAL
	207	select CRYPTO
	208	---help---
	209	This device-mapper target allows you to create a device that
	210	transparently encrypts the data on it. You'll need to activate
	211	the ciphers you're going to use in the cryptoapi configuration.
	212
	213	Information on how to use dm-crypt can be found on
	214
	215	<http://www.saout.de/misc/dm-crypt/>
	216
	217	To compile this code as a module, choose M here: the module will
	218	be called dm-crypt.
	219
	220	If unsure, say N.
	221
	222	config DM_SNAPSHOT
	223	tristate "Snapshot target (EXPERIMENTAL)"
	224	depends on BLK_DEV_DM && EXPERIMENTAL
	225	---help---
4d2554d0	226	Allow volume managers to take writable snapshots of a device.
1da177e4 LT	227
	228	config DM_MIRROR
	229	tristate "Mirror target (EXPERIMENTAL)"
	230	depends on BLK_DEV_DM && EXPERIMENTAL
	231	---help---
	232	Allow volume managers to mirror logical volumes, also
	233	needed for live data migration tools such as 'pvmove'.
	234
	235	config DM_ZERO
	236	tristate "Zero target (EXPERIMENTAL)"
	237	depends on BLK_DEV_DM && EXPERIMENTAL
	238	---help---
	239	A target that discards writes, and returns all zeroes for
	240	reads. Useful in some recovery situations.
	241
	242	config DM_MULTIPATH
	243	tristate "Multipath target (EXPERIMENTAL)"
	244	depends on BLK_DEV_DM && EXPERIMENTAL
	245	---help---
	246	Allow volume managers to support multipath hardware.
	247
	248	config DM_MULTIPATH_EMC
	249	tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
	250	depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
	251	---help---
	252	Multipath support for EMC CX/AX series hardware.
	253
	254	endmenu
	255
9361401e	256	endif