drivers/md/Kconfig

   1 #
   2 # Block device driver configuration
   3 #
   4
   5 menuconfig MD
   6         bool "Multiple devices driver support (RAID and LVM)"
   7         depends on BLOCK
   8         help
   9           Support multiple physical spindles through a single logical device.
  10           Required for RAID and logical volume management.
  11
  12 if MD
  13
  14 config BLK_DEV_MD
  15         tristate "RAID support"
  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_AUTODETECT
  34         bool "Autodetect RAID arrays during kernel boot"
  35         depends on BLK_DEV_MD=y
  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
  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
 107           mirroring (RAID-1) with easier configuration and more flexible
 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
 121 config MD_RAID456
 122         tristate "RAID-4/RAID-5/RAID-6 mode"
 123         depends on BLK_DEV_MD
 124         select ASYNC_MEMCPY
 125         select ASYNC_XOR
 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
 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
 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
 148           If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y.  To
 149           compile this code as a module, choose M here: the module
 150           will be called raid456.
 151
 152           If unsure, say Y.
 153
 154 config MD_RAID5_RESHAPE
 155         bool "Support adding drives to a raid-5 array"
 156         depends on MD_RAID456
 157         default y
 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
 164           is online.
 165
 166           You will need mdadm version 2.4.1 or later to use this
 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.
 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
 181           If unsure, say Y.
 182
 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"
 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
 219 config DM_DEBUG
 220         boolean "Device mapper debugging support"
 221         depends on BLK_DEV_DM
 222         ---help---
 223           Enable this for messages that may help debug device-mapper problems.
 224
 225           If unsure, say N.
 226
 227 config DM_CRYPT
 228         tristate "Crypt target support"
 229         depends on BLK_DEV_DM
 230         select CRYPTO
 231         select CRYPTO_CBC
 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
 247        tristate "Snapshot target"
 248        depends on BLK_DEV_DM
 249        ---help---
 250          Allow volume managers to take writable snapshots of a device.
 251
 252 config DM_MIRROR
 253        tristate "Mirror target"
 254        depends on BLK_DEV_DM
 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
 260         tristate "Zero target"
 261         depends on BLK_DEV_DM
 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
 267         tristate "Multipath target"
 268         depends on BLK_DEV_DM
 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
 274         ---help---
 275           Allow volume managers to support multipath hardware.
 276
 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
 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
 292 endif # MD