# SPDX-License-Identifier: GPL-2.0-only # # 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 . 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 . 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 . 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 . 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" 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. Currently, it can work with raid1 and raid10 (limited support). 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 depends on DAX || DAX=n 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 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_UNSTRIPED tristate "Unstriped target" depends on BLK_DEV_DM help Unstripes I/O so it is issued solely on a single drive in a HW RAID0 or dm-striped target. config DM_CRYPT tristate "Crypt target support" depends on BLK_DEV_DM depends on (ENCRYPTED_KEYS || ENCRYPTED_KEYS=n) select CRYPTO select CRYPTO_CBC select CRYPTO_ESSIV 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: To compile this code as a module, choose M here: the module will be called dm-crypt. If unsure, say N. config DM_DEFAULT_KEY tristate "Default-key target support" depends on BLK_DEV_DM depends on BLK_INLINE_ENCRYPTION # dm-default-key doesn't require -o inlinecrypt, but it does currently # rely on the inline encryption hooks being built into the kernel. depends on FS_ENCRYPTION_INLINE_CRYPT help This device-mapper target allows you to create a device that assigns a default encryption key to bios that aren't for the contents of an encrypted file. This ensures that all blocks on-disk will be encrypted with some key, without the performance hit of file contents being encrypted twice when fscrypt (File-Based Encryption) is used. It is only appropriate to use dm-default-key when key configuration is tightly controlled, like it is in Android, such that all fscrypt keys are at least as hard to compromise as the default key. 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_WRITECACHE tristate "Writecache target" depends on BLK_DEV_DM help The writecache target caches writes on persistent memory or SSD. It is intended for databases or other programs that need extremely low commit latency. The writecache target doesn't cache reads because reads are supposed to be cached in standard RAM. config DM_EBS tristate "Emulated block size target (EXPERIMENTAL)" depends on BLK_DEV_DM select DM_BUFIO help dm-ebs emulates smaller logical block size on backing devices with larger ones (e.g. 512 byte sectors on 4K native disks). 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_CLONE tristate "Clone target (EXPERIMENTAL)" depends on BLK_DEV_DM default n select DM_PERSISTENT_DATA help dm-clone produces a one-to-one copy of an existing, read-only source device into a writable destination device. The cloned device is visible/mountable immediately and the copy of the source device to the destination device happens in the background, in parallel with user I/O. If unsure, say N. 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_MULTIPATH_HST tristate "I/O Path Selector based on historical 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 by comparing estimated service time (based on historical service 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_DUST tristate "Bad sector simulation target" depends on BLK_DEV_DM help A target that simulates bad sector behavior. Useful for testing. If unsure, say N. config DM_INIT bool "DM \"dm-mod.create=\" parameter support" depends on BLK_DEV_DM=y help Enable "dm-mod.create=" parameter to create mapped devices at init time. This option is useful to allow mounting rootfs without requiring an initramfs. See Documentation/admin-guide/device-mapper/dm-init.rst for dm-mod.create="..." format. 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_VERIFY_ROOTHASH_SIG def_bool n bool "Verity data device root hash signature verification support" depends on DM_VERITY select SYSTEM_DATA_VERIFICATION help Add ability for dm-verity device to be validated if the pre-generated tree of cryptographic checksums passed has a pkcs#7 signature file that can validate the roothash of the tree. 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 CRYPTO_SKCIPHER 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 select CRC32 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. config DM_BOW tristate "Backup block device" depends on BLK_DEV_DM select DM_BUFIO help This device-mapper target takes a device and keeps a log of all changes using free blocks identified by issuing a trim command. This can then be restored by running a command line utility, or committed by simply replacing the target. If unsure, say N. config DM_USER tristate "Block device in userspace" depends on BLK_DEV_DM default y help This device-mapper target allows a userspace daemon to provide the contents of a block device. See for more information. To compile this code as a module, choose M here: the module will be called dm-user. If unsure, say N. endif # MD