drivers/md/Kconfig

   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 flexible
  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_RAID456
 108         tristate "RAID-4/RAID-5/RAID-6 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           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
 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
 132           If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y.  To
 133           compile this code as a module, choose M here: the module
 134           will be called raid456.
 135
 136           If unsure, say Y.
 137
 138 config MD_RAID5_RESHAPE
 139         bool "Support adding drives to a raid-5 array (experimental)"
 140         depends on MD_RAID456 && 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
 150           You will need mdadm version 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.
 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
 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 writable 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