drivers/md/Kconfig

   1 #
   2 # Block device driver configuration
   3 #
   4
   5 if BLOCK
   6
   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
  95           mirroring (RAID-1) with easier configuration and more flexible
  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
 109 config MD_RAID456
 110         tristate "RAID-4/RAID-5/RAID-6 mode"
 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
 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
 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
 134           If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y.  To
 135           compile this code as a module, choose M here: the module
 136           will be called raid456.
 137
 138           If unsure, say Y.
 139
 140 config MD_RAID5_RESHAPE
 141         bool "Support adding drives to a raid-5 array"
 142         depends on MD_RAID456
 143         default y
 144         ---help---
 145           A RAID-5 set can be expanded by adding extra drives. This
 146           requires "restriping" the array which means (almost) every
 147           block must be written to a different place.
 148
 149           This option allows such restriping to be done while the array
 150           is online.
 151
 152           You will need mdadm version 2.4.1 or later to use this
 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.
 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
 167           If unsure, say Y.
 168
 169 config MD_MULTIPATH
 170         tristate "Multipath I/O support"
 171         depends on BLK_DEV_MD
 172         help
 173           Multipath-IO is the ability of certain devices to address the same
 174           physical disk over multiple 'IO paths'. The code ensures that such
 175           paths can be defined and handled at runtime, and ensures that a
 176           transparent failover to the backup path(s) happens if a IO errors
 177           arrives on the primary path.
 178
 179           If unsure, say N.
 180
 181 config MD_FAULTY
 182         tristate "Faulty test module for MD"
 183         depends on BLK_DEV_MD
 184         help
 185           The "faulty" module allows for a block device that occasionally returns
 186           read or write errors.  It is useful for testing.
 187
 188           In unsure, say N.
 189
 190 config BLK_DEV_DM
 191         tristate "Device mapper support"
 192         depends on MD
 193         ---help---
 194           Device-mapper is a low level volume manager.  It works by allowing
 195           people to specify mappings for ranges of logical sectors.  Various
 196           mapping types are available, in addition people may write their own
 197           modules containing custom mappings if they wish.
 198
 199           Higher level volume managers such as LVM2 use this driver.
 200
 201           To compile this as a module, choose M here: the module will be
 202           called dm-mod.
 203
 204           If unsure, say N.
 205
 206 config DM_DEBUG
 207         boolean "Device mapper debugging support"
 208         depends on BLK_DEV_DM && EXPERIMENTAL
 209         ---help---
 210           Enable this for messages that may help debug device-mapper problems.
 211
 212           If unsure, say N.
 213
 214 config DM_CRYPT
 215         tristate "Crypt target support"
 216         depends on BLK_DEV_DM && EXPERIMENTAL
 217         select CRYPTO
 218         select CRYPTO_CBC
 219         ---help---
 220           This device-mapper target allows you to create a device that
 221           transparently encrypts the data on it. You'll need to activate
 222           the ciphers you're going to use in the cryptoapi configuration.
 223
 224           Information on how to use dm-crypt can be found on
 225
 226           <http://www.saout.de/misc/dm-crypt/>
 227
 228           To compile this code as a module, choose M here: the module will
 229           be called dm-crypt.
 230
 231           If unsure, say N.
 232
 233 config DM_SNAPSHOT
 234        tristate "Snapshot target (EXPERIMENTAL)"
 235        depends on BLK_DEV_DM && EXPERIMENTAL
 236        ---help---
 237          Allow volume managers to take writable snapshots of a device.
 238
 239 config DM_MIRROR
 240        tristate "Mirror target (EXPERIMENTAL)"
 241        depends on BLK_DEV_DM && EXPERIMENTAL
 242        ---help---
 243          Allow volume managers to mirror logical volumes, also
 244          needed for live data migration tools such as 'pvmove'.
 245
 246 config DM_ZERO
 247         tristate "Zero target (EXPERIMENTAL)"
 248         depends on BLK_DEV_DM && EXPERIMENTAL
 249         ---help---
 250           A target that discards writes, and returns all zeroes for
 251           reads.  Useful in some recovery situations.
 252
 253 config DM_MULTIPATH
 254         tristate "Multipath target (EXPERIMENTAL)"
 255         depends on BLK_DEV_DM && EXPERIMENTAL
 256         ---help---
 257           Allow volume managers to support multipath hardware.
 258
 259 config DM_MULTIPATH_EMC
 260         tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
 261         depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
 262         ---help---
 263           Multipath support for EMC CX/AX series hardware.
 264
 265 config DM_DELAY
 266         tristate "I/O delaying target (EXPERIMENTAL)"
 267         depends on BLK_DEV_DM && EXPERIMENTAL
 268         ---help---
 269         A target that delays reads and/or writes and can send
 270         them to different devices.  Useful for testing.
 271
 272         If unsure, say N.
 273
 274 endmenu
 275
 276 endif