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linux/drivers/md/Kconfig
Damien Le Moal 3b1a94c88b dm zoned: drive-managed zoned block device target 
The dm-zoned device mapper target provides transparent write access
to zoned block devices (ZBC and ZAC compliant block devices).
dm-zoned hides to the device user (a file system or an application
doing raw block device accesses) any constraint imposed on write
requests by the device, equivalent to a drive-managed zoned block
device model.

Write requests are processed using a combination of on-disk buffering
using the device conventional zones and direct in-place processing for
requests aligned to a zone sequential write pointer position.
A background reclaim process implemented using dm_kcopyd_copy ensures
that conventional zones are always available for executing unaligned
write requests. The reclaim process overhead is minimized by managing
buffer zones in a least-recently-written order and first targeting the
oldest buffer zones. Doing so, blocks under regular write access (such
as metadata blocks of a file system) remain stored in conventional
zones, resulting in no apparent overhead.

dm-zoned implementation focus on simplicity and on minimizing overhead
(CPU, memory and storage overhead). For a 14TB host-managed disk with
256 MB zones, dm-zoned memory usage per disk instance is at most about
3 MB and as little as 5 zones will be used internally for storing metadata
and performing buffer zone reclaim operations. This is achieved using
zone level indirection rather than a full block indirection system for
managing block movement between zones.

dm-zoned primary target is host-managed zoned block devices but it can
also be used with host-aware device models to mitigate potential
device-side performance degradation due to excessive random writing.

Zoned block devices can be formatted and checked for use with the dm-zoned
target using the dmzadm utility available at:

https://github.com/hgst/dm-zoned-tools

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
[Mike Snitzer partly refactored Damien's original work to cleanup the code]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-06-19 11:05:20 -04:00

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#
# Block device driver configuration
#
menuconfig MD
bool "Multiple devices driver support (RAID and LVM)"
depends on BLOCK
select SRCU
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:
https://www.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 LIBCRC32C
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 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 MD_CLUSTER
tristate "Cluster Support for MD (EXPERIMENTAL)"
depends on BLK_DEV_MD
depends on DLM
default n
---help---
Clustering support for MD devices. This enables locking and
synchronization across multiple systems on the cluster, so all
nodes in the cluster can access the MD devices simultaneously.
This brings the redundancy (and uptime) of RAID levels across the
nodes of the cluster.
If unsure, say N.
source "drivers/md/bcache/Kconfig"
config BLK_DEV_DM_BUILTIN
bool
config BLK_DEV_DM
tristate "Device mapper support"
select BLK_DEV_DM_BUILTIN
select DAX
---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_MQ_DEFAULT
bool "request-based DM: use blk-mq I/O path by default"
depends on BLK_DEV_DM
---help---
This option enables the blk-mq based I/O path for request-based
DM devices by default. With the option the dm_mod.use_blk_mq
module/boot option defaults to Y, without it to N, but it can
still be overriden either way.
If unsure say N.
config DM_DEBUG
bool "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_BUFIO
tristate
depends on BLK_DEV_DM
---help---
This interface allows you to do buffered I/O on a device and acts
as a cache, holding recently-read blocks in memory and performing
delayed writes.
config DM_DEBUG_BLOCK_MANAGER_LOCKING
bool "Block manager locking"
depends on DM_BUFIO
---help---
Block manager locking can catch various metadata corruption issues.
If unsure, say N.
config DM_DEBUG_BLOCK_STACK_TRACING
bool "Keep stack trace of persistent data block lock holders"
depends on STACKTRACE_SUPPORT && DM_DEBUG_BLOCK_MANAGER_LOCKING
select STACKTRACE
---help---
Enable this for messages that may help debug problems with the
block manager locking used by thin provisioning and caching.
If unsure, say N.
config DM_BIO_PRISON
tristate
depends on BLK_DEV_DM
---help---
Some bio locking schemes used by other device-mapper targets
including thin provisioning.
source "drivers/md/persistent-data/Kconfig"
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.
For further information on dm-crypt and userspace tools see:
<https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt>
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
select DM_BUFIO
---help---
Allow volume managers to take writable snapshots of a device.
config DM_THIN_PROVISIONING
tristate "Thin provisioning target"
depends on BLK_DEV_DM
select DM_PERSISTENT_DATA
select DM_BIO_PRISON
---help---
Provides thin provisioning and snapshots that share a data store.
config DM_CACHE
tristate "Cache target (EXPERIMENTAL)"
depends on BLK_DEV_DM
default n
select DM_PERSISTENT_DATA
select DM_BIO_PRISON
---help---
dm-cache attempts to improve performance of a block device by
moving frequently used data to a smaller, higher performance
device. Different 'policy' plugins can be used to change the
algorithms used to select which blocks are promoted, demoted,
cleaned etc. It supports writeback and writethrough modes.
config DM_CACHE_SMQ
tristate "Stochastic MQ Cache Policy (EXPERIMENTAL)"
depends on DM_CACHE
default y
---help---
A cache policy that uses a multiqueue ordered by recent hits
to select which blocks should be promoted and demoted.
This is meant to be a general purpose policy. It prioritises
reads over writes. This SMQ policy (vs MQ) offers the promise
of less memory utilization, improved performance and increased
adaptability in the face of changing workloads.
config DM_ERA
tristate "Era target (EXPERIMENTAL)"
depends on BLK_DEV_DM
default n
select DM_PERSISTENT_DATA
select DM_BIO_PRISON
---help---
dm-era tracks which parts of a block device are written to
over time. Useful for maintaining cache coherency when using
vendor snapshots.
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_LOG_USERSPACE
tristate "Mirror userspace logging"
depends on DM_MIRROR && 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_RAID
tristate "RAID 1/4/5/6/10 target"
depends on BLK_DEV_DM
select MD_RAID0
select MD_RAID1
select MD_RAID10
select MD_RAID456
select BLK_DEV_MD
---help---
A dm target that supports RAID1, RAID10, 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_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
---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"
depends on BLK_DEV_DM
---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"
depends on BLK_DEV_DM
---help---
Generate udev events for DM events.
config DM_FLAKEY
tristate "Flakey target"
depends on BLK_DEV_DM
---help---
A target that intermittently fails I/O for debugging purposes.
config DM_VERITY
tristate "Verity target support"
depends on BLK_DEV_DM
select CRYPTO
select CRYPTO_HASH
select DM_BUFIO
---help---
This device-mapper target creates a read-only device that
transparently validates the data on one underlying device against
a pre-generated tree of cryptographic checksums stored on a second
device.
You'll need to activate the digests you're going to use in the
cryptoapi configuration.
To compile this code as a module, choose M here: the module will
be called dm-verity.
If unsure, say N.
config DM_VERITY_FEC
bool "Verity forward error correction support"
depends on DM_VERITY
select REED_SOLOMON
select REED_SOLOMON_DEC8
---help---
Add forward error correction support to dm-verity. This option
makes it possible to use pre-generated error correction data to
recover from corrupted blocks.
If unsure, say N.
config DM_SWITCH
tristate "Switch target support (EXPERIMENTAL)"
depends on BLK_DEV_DM
---help---
This device-mapper target creates a device that supports an arbitrary
mapping of fixed-size regions of I/O across a fixed set of paths.
The path used for any specific region can be switched dynamically
by sending the target a message.
To compile this code as a module, choose M here: the module will
be called dm-switch.
If unsure, say N.
config DM_LOG_WRITES
tristate "Log writes target support"
depends on BLK_DEV_DM
---help---
This device-mapper target takes two devices, one device to use
normally, one to log all write operations done to the first device.
This is for use by file system developers wishing to verify that
their fs is writing a consistent file system at all times by allowing
them to replay the log in a variety of ways and to check the
contents.
To compile this code as a module, choose M here: the module will
be called dm-log-writes.
If unsure, say N.
config DM_INTEGRITY
tristate "Integrity target support"
depends on BLK_DEV_DM
select BLK_DEV_INTEGRITY
select DM_BUFIO
select CRYPTO
select ASYNC_XOR
---help---
This device-mapper target emulates a block device that has
additional per-sector tags that can be used for storing
integrity information.
This integrity target is used with the dm-crypt target to
provide authenticated disk encryption or it can be used
standalone.
To compile this code as a module, choose M here: the module will
be called dm-integrity.
config DM_ZONED
tristate "Drive-managed zoned block device target support"
depends on BLK_DEV_DM
depends on BLK_DEV_ZONED
---help---
This device-mapper target takes a host-managed or host-aware zoned
block device and exposes most of its capacity as a regular block
device (drive-managed zoned block device) without any write
constraints. This is mainly intended for use with file systems that
do not natively support zoned block devices but still want to
benefit from the increased capacity offered by SMR disks. Other uses
by applications using raw block devices (for example object stores)
are also possible.
To compile this code as a module, choose M here: the module will
be called dm-zoned.
If unsure, say N.
endif # MD
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