![Jonathan Brassow](/assets/img/avatar_default.png)
Add the ability to parse and use metadata devices to dm-raid. Although not strictly required, without the metadata devices, many features of RAID are unavailable. They are used to store a superblock and bitmap. The role, or position in the array, of each device must be recorded in its superblock. This is to help with fault handling, array reshaping, and sanity checks. RAID 4/5/6 devices must be loaded in a specific order: in this way, the 'array_position' field helps validate the correctness of the mapping when it is loaded. It can be used during reshaping to identify which devices are added/removed. Fault handling is impossible without this field. For example, when a device fails it is recorded in the superblock. If this is a RAID1 device and the offending device is removed from the array, there must be a way during subsequent array assembly to determine that the failed device was the one removed. This is done by correlating the 'array_position' field and the bit-field variable 'failed_devices'. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
338 lines
11 KiB
Plaintext
338 lines
11 KiB
Plaintext
#
|
|
# 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_AUTODETECT
|
|
bool "Autodetect RAID arrays during kernel boot"
|
|
depends on BLK_DEV_MD=y
|
|
default y
|
|
---help---
|
|
If you say Y here, then the kernel will try to autodetect raid
|
|
arrays as part of its boot process.
|
|
|
|
If you don't use raid and say Y, this autodetection can cause
|
|
a several-second delay in the boot time due to various
|
|
synchronisation steps that are part of this step.
|
|
|
|
If unsure, say Y.
|
|
|
|
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"
|
|
depends on BLK_DEV_MD
|
|
---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 RAID6_PQ
|
|
select ASYNC_MEMCPY
|
|
select ASYNC_XOR
|
|
select ASYNC_PQ
|
|
select ASYNC_RAID6_RECOV
|
|
---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 MULTICORE_RAID456
|
|
bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
|
|
depends on MD_RAID456
|
|
depends on SMP
|
|
depends on EXPERIMENTAL
|
|
---help---
|
|
Enable the raid456 module to dispatch per-stripe raid operations to a
|
|
thread pool.
|
|
|
|
If unsure, say N.
|
|
|
|
config MD_MULTIPATH
|
|
tristate "Multipath I/O support"
|
|
depends on BLK_DEV_MD
|
|
help
|
|
MD_MULTIPATH provides a simple multi-path personality for use
|
|
the MD framework. It is not under active development. New
|
|
projects should consider using DM_MULTIPATH which has more
|
|
features and more testing.
|
|
|
|
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
|
|
---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
|
|
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"
|
|
depends on BLK_DEV_DM
|
|
---help---
|
|
Allow volume managers to take writable snapshots of a device.
|
|
|
|
config DM_MIRROR
|
|
tristate "Mirror target"
|
|
depends on BLK_DEV_DM
|
|
---help---
|
|
Allow volume managers to mirror logical volumes, also
|
|
needed for live data migration tools such as 'pvmove'.
|
|
|
|
config DM_RAID
|
|
tristate "RAID 1/4/5/6 target (EXPERIMENTAL)"
|
|
depends on BLK_DEV_DM && EXPERIMENTAL
|
|
select MD_RAID1
|
|
select MD_RAID456
|
|
select BLK_DEV_MD
|
|
---help---
|
|
A dm target that supports RAID1, RAID4, RAID5 and RAID6 mappings
|
|
|
|
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.
|
|
|
|
config DM_LOG_USERSPACE
|
|
tristate "Mirror userspace logging (EXPERIMENTAL)"
|
|
depends on DM_MIRROR && EXPERIMENTAL && NET
|
|
select CONNECTOR
|
|
---help---
|
|
The userspace logging module provides a mechanism for
|
|
relaying the dm-dirty-log API to userspace. Log designs
|
|
which are more suited to userspace implementation (e.g.
|
|
shared storage logs) or experimental logs can be implemented
|
|
by leveraging this framework.
|
|
|
|
config DM_ZERO
|
|
tristate "Zero target"
|
|
depends on BLK_DEV_DM
|
|
---help---
|
|
A target that discards writes, and returns all zeroes for
|
|
reads. Useful in some recovery situations.
|
|
|
|
config DM_MULTIPATH
|
|
tristate "Multipath target"
|
|
depends on BLK_DEV_DM
|
|
# nasty syntax but means make DM_MULTIPATH independent
|
|
# of SCSI_DH if the latter isn't defined but if
|
|
# it is, DM_MULTIPATH must depend on it. We get a build
|
|
# error if SCSI_DH=m and DM_MULTIPATH=y
|
|
depends on SCSI_DH || !SCSI_DH
|
|
---help---
|
|
Allow volume managers to support multipath hardware.
|
|
|
|
config DM_MULTIPATH_QL
|
|
tristate "I/O Path Selector based on the number of in-flight I/Os"
|
|
depends on DM_MULTIPATH
|
|
---help---
|
|
This path selector is a dynamic load balancer which selects
|
|
the path with the least number of in-flight I/Os.
|
|
|
|
If unsure, say N.
|
|
|
|
config DM_MULTIPATH_ST
|
|
tristate "I/O Path Selector based on the service time"
|
|
depends on DM_MULTIPATH
|
|
---help---
|
|
This path selector is a dynamic load balancer which selects
|
|
the path expected to complete the incoming I/O in the shortest
|
|
time.
|
|
|
|
If unsure, say N.
|
|
|
|
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.
|
|
|
|
config DM_FLAKEY
|
|
tristate "Flakey target (EXPERIMENTAL)"
|
|
depends on BLK_DEV_DM && EXPERIMENTAL
|
|
---help---
|
|
A target that intermittently fails I/O for debugging purposes.
|
|
|
|
endif # MD
|