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# Block device driver configuration
#

menuconfig MD
        bool "Multiple devices driver support (RAID and LVM)"
        depends on BLOCK
        help
          Support multiple physical spindles through a single logical device.
          Required for RAID and logical volume management.

if MD

config BLK_DEV_MD
        tristate "RAID support"
        ---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
        select ASYNC_MEMCPY
        select ASYNC_XOR
        ---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"
        depends on MD_RAID456
        default y
        ---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.

          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.

          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"
        ---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_DEBUG
        boolean "Device mapper debugging support"
        depends on BLK_DEV_DM && EXPERIMENTAL
        ---help---
          Enable this for messages that may help debug device-mapper problems.

          If unsure, say N.

config DM_CRYPT
        tristate "Crypt target support"
        depends on BLK_DEV_DM && EXPERIMENTAL
        select CRYPTO
        select CRYPTO_CBC
        ---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.

config DM_MULTIPATH_RDAC
        tristate "LSI/Engenio RDAC multipath support (EXPERIMENTAL)"
        depends on DM_MULTIPATH && BLK_DEV_DM && SCSI && EXPERIMENTAL
        ---help---
          Multipath support for LSI/Engenio RDAC.

config DM_MULTIPATH_HP
        tristate "HP MSA multipath support (EXPERIMENTAL)"
        depends on DM_MULTIPATH && BLK_DEV_DM && SCSI && EXPERIMENTAL
        ---help---
          Multipath support for HP MSA (Active/Passive) series hardware.

config DM_DELAY
        tristate "I/O delaying target (EXPERIMENTAL)"
        depends on BLK_DEV_DM && EXPERIMENTAL
        ---help---
        A target that delays reads and/or writes and can send
        them to different devices.  Useful for testing.

        If unsure, say N.

config DM_UEVENT
        bool "DM uevents (EXPERIMENTAL)"
        depends on BLK_DEV_DM && EXPERIMENTAL
        ---help---
        Generate udev events for DM events.

endif # MD