linux/drivers/md/Kconfig

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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:
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 LIBCRC32C
async_tx: add the async_tx api The async_tx api provides methods for describing a chain of asynchronous bulk memory transfers/transforms with support for inter-transactional dependencies. It is implemented as a dmaengine client that smooths over the details of different hardware offload engine implementations. Code that is written to the api can optimize for asynchronous operation and the api will fit the chain of operations to the available offload resources. I imagine that any piece of ADMA hardware would register with the 'async_*' subsystem, and a call to async_X would be routed as appropriate, or be run in-line. - Neil Brown async_tx exploits the capabilities of struct dma_async_tx_descriptor to provide an api of the following general format: struct dma_async_tx_descriptor * async_<operation>(..., struct dma_async_tx_descriptor *depend_tx, dma_async_tx_callback cb_fn, void *cb_param) { struct dma_chan *chan = async_tx_find_channel(depend_tx, <operation>); struct dma_device *device = chan ? chan->device : NULL; int int_en = cb_fn ? 1 : 0; struct dma_async_tx_descriptor *tx = device ? device->device_prep_dma_<operation>(chan, len, int_en) : NULL; if (tx) { /* run <operation> asynchronously */ ... tx->tx_set_dest(addr, tx, index); ... tx->tx_set_src(addr, tx, index); ... async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); } else { /* run <operation> synchronously */ ... <operation> ... async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); } return tx; } async_tx_find_channel() returns a capable channel from its pool. The channel pool is organized as a per-cpu array of channel pointers. The async_tx_rebalance() routine is tasked with managing these arrays. In the uniprocessor case async_tx_rebalance() tries to spread responsibility evenly over channels of similar capabilities. For example if there are two copy+xor channels, one will handle copy operations and the other will handle xor. In the SMP case async_tx_rebalance() attempts to spread the operations evenly over the cpus, e.g. cpu0 gets copy channel0 and xor channel0 while cpu1 gets copy channel 1 and xor channel 1. When a dependency is specified async_tx_find_channel defaults to keeping the operation on the same channel. A xor->copy->xor chain will stay on one channel if it supports both operation types, otherwise the transaction will transition between a copy and a xor resource. Currently the raid5 implementation in the MD raid456 driver has been converted to the async_tx api. A driver for the offload engines on the Intel Xscale series of I/O processors, iop-adma, is provided in a later commit. With the iop-adma driver and async_tx, raid456 is able to offload copy, xor, and xor-zero-sum operations to hardware engines. On iop342 tiobench showed higher throughput for sequential writes (20 - 30% improvement) and sequential reads to a degraded array (40 - 55% improvement). For the other cases performance was roughly equal, +/- a few percentage points. On a x86-smp platform the performance of the async_tx implementation (in synchronous mode) was also +/- a few percentage points of the original implementation. According to 'top' on iop342 CPU utilization drops from ~50% to ~15% during a 'resync' while the speed according to /proc/mdstat doubles from ~25 MB/s to ~50 MB/s. The tiobench command line used for testing was: tiobench --size 2048 --block 4096 --block 131072 --dir /mnt/raid --numruns 5 * iop342 had 1GB of memory available Details: * if CONFIG_DMA_ENGINE=n the asynchronous path is compiled away by making async_tx_find_channel a static inline routine that always returns NULL * when a callback is specified for a given transaction an interrupt will fire at operation completion time and the callback will occur in a tasklet. if the the channel does not support interrupts then a live polling wait will be performed * the api is written as a dmaengine client that requests all available channels * In support of dependencies the api implicitly schedules channel-switch interrupts. The interrupt triggers the cleanup tasklet which causes pending operations to be scheduled on the next channel * Xor engines treat an xor destination address differently than a software xor routine. To the software routine the destination address is an implied source, whereas engines treat it as a write-only destination. This patch modifies the xor_blocks routine to take a an explicit destination address to mirror the hardware. Changelog: * fixed a leftover debug print * don't allow callbacks in async_interrupt_cond * fixed xor_block changes * fixed usage of ASYNC_TX_XOR_DROP_DEST * drop dma mapping methods, suggested by Chris Leech * printk warning fixups from Andrew Morton * don't use inline in C files, Adrian Bunk * select the API when MD is enabled * BUG_ON xor source counts <= 1 * implicitly handle hardware concerns like channel switching and interrupts, Neil Brown * remove the per operation type list, and distribute operation capabilities evenly amongst the available channels * simplify async_tx_find_channel to optimize the fast path * introduce the channel_table_initialized flag to prevent early calls to the api * reorganize the code to mimic crypto * include mm.h as not all archs include it in dma-mapping.h * make the Kconfig options non-user visible, Adrian Bunk * move async_tx under crypto since it is meant as 'core' functionality, and the two may share algorithms in the future * move large inline functions into c files * checkpatch.pl fixes * gpl v2 only correction Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-By: NeilBrown <neilb@suse.de>
2007-01-02 19:10:44 +01:00
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
---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_STACK_TRACING
bool "Keep stack trace of persistent data block lock holders"
depends on STACKTRACE_SUPPORT && DM_BUFIO
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.
dm cache: add stochastic-multi-queue (smq) policy The stochastic-multi-queue (smq) policy addresses some of the problems with the current multiqueue (mq) policy. Memory usage ------------ The mq policy uses a lot of memory; 88 bytes per cache block on a 64 bit machine. SMQ uses 28bit indexes to implement it's data structures rather than pointers. It avoids storing an explicit hit count for each block. It has a 'hotspot' queue rather than a pre cache which uses a quarter of the entries (each hotspot block covers a larger area than a single cache block). All these mean smq uses ~25bytes per cache block. Still a lot of memory, but a substantial improvement nontheless. Level balancing --------------- MQ places entries in different levels of the multiqueue structures based on their hit count (~ln(hit count)). This means the bottom levels generally have the most entries, and the top ones have very few. Having unbalanced levels like this reduces the efficacy of the multiqueue. SMQ does not maintain a hit count, instead it swaps hit entries with the least recently used entry from the level above. The over all ordering being a side effect of this stochastic process. With this scheme we can decide how many entries occupy each multiqueue level, resulting in better promotion/demotion decisions. Adaptability ------------ The MQ policy maintains a hit count for each cache block. For a different block to get promoted to the cache it's hit count has to exceed the lowest currently in the cache. This means it can take a long time for the cache to adapt between varying IO patterns. Periodically degrading the hit counts could help with this, but I haven't found a nice general solution. SMQ doesn't maintain hit counts, so a lot of this problem just goes away. In addition it tracks performance of the hotspot queue, which is used to decide which blocks to promote. If the hotspot queue is performing badly then it starts moving entries more quickly between levels. This lets it adapt to new IO patterns very quickly. Performance ----------- In my tests SMQ shows substantially better performance than MQ. Once this matures a bit more I'm sure it'll become the default policy. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-05-15 16:33:34 +02:00
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_CACHE_CLEANER
tristate "Cleaner Cache Policy (EXPERIMENTAL)"
depends on DM_CACHE
default y
---help---
A simple cache policy that writes back all data to the
origin. Used when decommissioning a dm-cache.
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.
dm: raid456 basic support This patch is the skeleton for the DM target that will be the bridge from DM to MD (initially RAID456 and later RAID1). It provides a way to use device-mapper interfaces to the MD RAID456 drivers. As with all device-mapper targets, the nominal public interfaces are the constructor (CTR) tables and the status outputs (both STATUSTYPE_INFO and STATUSTYPE_TABLE). The CTR table looks like the following: 1: <s> <l> raid \ 2: <raid_type> <#raid_params> <raid_params> \ 3: <#raid_devs> <meta_dev1> <dev1> .. <meta_devN> <devN> Line 1 contains the standard first three arguments to any device-mapper target - the start, length, and target type fields. The target type in this case is "raid". Line 2 contains the arguments that define the particular raid type/personality/level, the required arguments for that raid type, and any optional arguments. Possible raid types include: raid4, raid5_la, raid5_ls, raid5_rs, raid6_zr, raid6_nr, and raid6_nc. (again, raid1 is planned for the future.) The list of required and optional parameters is the same for all the current raid types. The required parameters are positional, while the optional parameters are given as key/value pairs. The possible parameters are as follows: <chunk_size> Chunk size in sectors. [[no]sync] Force/Prevent RAID initialization [rebuild <idx>] Rebuild the drive indicated by the index [daemon_sleep <ms>] Time between bitmap daemon work to clear bits [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_write_behind <value>] See '-write-behind=' (man mdadm) [stripe_cache <sectors>] Stripe cache size for higher RAIDs Line 3 contains the list of devices that compose the array in metadata/data device pairs. If the metadata is stored separately, a '-' is given for the metadata device position. If a drive has failed or is missing at creation time, a '-' can be given for both the metadata and data drives for a given position. Examples: # RAID4 - 4 data drives, 1 parity # No metadata devices specified to hold superblock/bitmap info # Chunk size of 1MiB # (Lines separated for easy reading) 0 1960893648 raid \ raid4 1 2048 \ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 # RAID4 - 4 data drives, 1 parity (no metadata devices) # Chunk size of 1MiB, force RAID initialization, # min recovery rate at 20 kiB/sec/disk 0 1960893648 raid \ raid4 4 2048 min_recovery_rate 20 sync\ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 Performing a 'dmsetup table' should display the CTR table used to construct the mapping (with possible reordering of optional parameters). Performing a 'dmsetup status' will yield information on the state and health of the array. The output is as follows: 1: <s> <l> raid \ 2: <raid_type> <#devices> <1 health char for each dev> <resync_ratio> Line 1 is standard DM output. Line 2 is best shown by example: 0 1960893648 raid raid4 5 AAAAA 2/490221568 Here we can see the RAID type is raid4, there are 5 devices - all of which are 'A'live, and the array is 2/490221568 complete with recovery. Cc: linux-raid@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-01-13 21:00:02 +01:00
config DM_RAID
tristate "RAID 1/4/5/6/10 target"
depends on BLK_DEV_DM
select MD_RAID1
select MD_RAID10
dm: raid456 basic support This patch is the skeleton for the DM target that will be the bridge from DM to MD (initially RAID456 and later RAID1). It provides a way to use device-mapper interfaces to the MD RAID456 drivers. As with all device-mapper targets, the nominal public interfaces are the constructor (CTR) tables and the status outputs (both STATUSTYPE_INFO and STATUSTYPE_TABLE). The CTR table looks like the following: 1: <s> <l> raid \ 2: <raid_type> <#raid_params> <raid_params> \ 3: <#raid_devs> <meta_dev1> <dev1> .. <meta_devN> <devN> Line 1 contains the standard first three arguments to any device-mapper target - the start, length, and target type fields. The target type in this case is "raid". Line 2 contains the arguments that define the particular raid type/personality/level, the required arguments for that raid type, and any optional arguments. Possible raid types include: raid4, raid5_la, raid5_ls, raid5_rs, raid6_zr, raid6_nr, and raid6_nc. (again, raid1 is planned for the future.) The list of required and optional parameters is the same for all the current raid types. The required parameters are positional, while the optional parameters are given as key/value pairs. The possible parameters are as follows: <chunk_size> Chunk size in sectors. [[no]sync] Force/Prevent RAID initialization [rebuild <idx>] Rebuild the drive indicated by the index [daemon_sleep <ms>] Time between bitmap daemon work to clear bits [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_write_behind <value>] See '-write-behind=' (man mdadm) [stripe_cache <sectors>] Stripe cache size for higher RAIDs Line 3 contains the list of devices that compose the array in metadata/data device pairs. If the metadata is stored separately, a '-' is given for the metadata device position. If a drive has failed or is missing at creation time, a '-' can be given for both the metadata and data drives for a given position. Examples: # RAID4 - 4 data drives, 1 parity # No metadata devices specified to hold superblock/bitmap info # Chunk size of 1MiB # (Lines separated for easy reading) 0 1960893648 raid \ raid4 1 2048 \ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 # RAID4 - 4 data drives, 1 parity (no metadata devices) # Chunk size of 1MiB, force RAID initialization, # min recovery rate at 20 kiB/sec/disk 0 1960893648 raid \ raid4 4 2048 min_recovery_rate 20 sync\ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 Performing a 'dmsetup table' should display the CTR table used to construct the mapping (with possible reordering of optional parameters). Performing a 'dmsetup status' will yield information on the state and health of the array. The output is as follows: 1: <s> <l> raid \ 2: <raid_type> <#devices> <1 health char for each dev> <resync_ratio> Line 1 is standard DM output. Line 2 is best shown by example: 0 1960893648 raid raid4 5 AAAAA 2/490221568 Here we can see the RAID type is raid4, there are 5 devices - all of which are 'A'live, and the array is 2/490221568 complete with recovery. Cc: linux-raid@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-01-13 21:00:02 +01:00
select MD_RAID456
select BLK_DEV_MD
---help---
A dm target that supports RAID1, RAID10, RAID4, RAID5 and RAID6 mappings
dm: raid456 basic support This patch is the skeleton for the DM target that will be the bridge from DM to MD (initially RAID456 and later RAID1). It provides a way to use device-mapper interfaces to the MD RAID456 drivers. As with all device-mapper targets, the nominal public interfaces are the constructor (CTR) tables and the status outputs (both STATUSTYPE_INFO and STATUSTYPE_TABLE). The CTR table looks like the following: 1: <s> <l> raid \ 2: <raid_type> <#raid_params> <raid_params> \ 3: <#raid_devs> <meta_dev1> <dev1> .. <meta_devN> <devN> Line 1 contains the standard first three arguments to any device-mapper target - the start, length, and target type fields. The target type in this case is "raid". Line 2 contains the arguments that define the particular raid type/personality/level, the required arguments for that raid type, and any optional arguments. Possible raid types include: raid4, raid5_la, raid5_ls, raid5_rs, raid6_zr, raid6_nr, and raid6_nc. (again, raid1 is planned for the future.) The list of required and optional parameters is the same for all the current raid types. The required parameters are positional, while the optional parameters are given as key/value pairs. The possible parameters are as follows: <chunk_size> Chunk size in sectors. [[no]sync] Force/Prevent RAID initialization [rebuild <idx>] Rebuild the drive indicated by the index [daemon_sleep <ms>] Time between bitmap daemon work to clear bits [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_write_behind <value>] See '-write-behind=' (man mdadm) [stripe_cache <sectors>] Stripe cache size for higher RAIDs Line 3 contains the list of devices that compose the array in metadata/data device pairs. If the metadata is stored separately, a '-' is given for the metadata device position. If a drive has failed or is missing at creation time, a '-' can be given for both the metadata and data drives for a given position. Examples: # RAID4 - 4 data drives, 1 parity # No metadata devices specified to hold superblock/bitmap info # Chunk size of 1MiB # (Lines separated for easy reading) 0 1960893648 raid \ raid4 1 2048 \ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 # RAID4 - 4 data drives, 1 parity (no metadata devices) # Chunk size of 1MiB, force RAID initialization, # min recovery rate at 20 kiB/sec/disk 0 1960893648 raid \ raid4 4 2048 min_recovery_rate 20 sync\ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 Performing a 'dmsetup table' should display the CTR table used to construct the mapping (with possible reordering of optional parameters). Performing a 'dmsetup status' will yield information on the state and health of the array. The output is as follows: 1: <s> <l> raid \ 2: <raid_type> <#devices> <1 health char for each dev> <resync_ratio> Line 1 is standard DM output. Line 2 is best shown by example: 0 1960893648 raid raid4 5 AAAAA 2/490221568 Here we can see the RAID type is raid4, there are 5 devices - all of which are 'A'live, and the array is 2/490221568 complete with recovery. Cc: linux-raid@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-01-13 21:00:02 +01:00
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.
endif # MD