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# Block device driver configuration
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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 flexable
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_RAID5
tristate "RAID-4/RAID-5 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.
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 set, say Y. To
compile this code as a module, choose M here: the module
will be called raid5.
If unsure, say Y.
config MD_RAID5_RESHAPE
bool "Support adding drives to a raid-5 array (experimental)"
depends on MD_RAID5 && 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 a version of mdadm newer than 2.3.1. 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_RAID6
tristate "RAID-6 mode"
depends on BLK_DEV_MD
---help---
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.
RAID-6 requires mdadm-1.5.0 or later, available at:
ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
If you want to use such a RAID-6 set, say Y. To compile
this code as a module, choose M here: the module will be
called raid6.
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"
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 writeable 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
