2 # Block device driver configuration
6 bool "Multiple devices driver support (RAID and LVM)"
9 Support multiple physical spindles through a single logical device.
10 Required for RAID and logical volume management.
15 tristate "RAID support"
17 This driver lets you combine several hard disk partitions into one
18 logical block device. This can be used to simply append one
19 partition to another one or to combine several redundant hard disks
20 into a RAID1/4/5 device so as to provide protection against hard
21 disk failures. This is called "Software RAID" since the combining of
22 the partitions is done by the kernel. "Hardware RAID" means that the
23 combining is done by a dedicated controller; if you have such a
24 controller, you do not need to say Y here.
26 More information about Software RAID on Linux is contained in the
27 Software RAID mini-HOWTO, available from
28 <http://www.tldp.org/docs.html#howto>. There you will also learn
29 where to get the supporting user space utilities raidtools.
34 bool "Autodetect RAID arrays during kernel boot"
35 depends on BLK_DEV_MD=y
38 If you say Y here, then the kernel will try to autodetect raid
39 arrays as part of its boot process.
41 If you don't use raid and say Y, this autodetection can cause
42 a several-second delay in the boot time due to various
43 synchronisation steps that are part of this step.
48 tristate "Linear (append) mode"
51 If you say Y here, then your multiple devices driver will be able to
52 use the so-called linear mode, i.e. it will combine the hard disk
53 partitions by simply appending one to the other.
55 To compile this as a module, choose M here: the module
56 will be called linear.
61 tristate "RAID-0 (striping) mode"
64 If you say Y here, then your multiple devices driver will be able to
65 use the so-called raid0 mode, i.e. it will combine the hard disk
66 partitions into one logical device in such a fashion as to fill them
67 up evenly, one chunk here and one chunk there. This will increase
68 the throughput rate if the partitions reside on distinct disks.
70 Information about Software RAID on Linux is contained in the
71 Software-RAID mini-HOWTO, available from
72 <http://www.tldp.org/docs.html#howto>. There you will also
73 learn where to get the supporting user space utilities raidtools.
75 To compile this as a module, choose M here: the module
81 tristate "RAID-1 (mirroring) mode"
84 A RAID-1 set consists of several disk drives which are exact copies
85 of each other. In the event of a mirror failure, the RAID driver
86 will continue to use the operational mirrors in the set, providing
87 an error free MD (multiple device) to the higher levels of the
88 kernel. In a set with N drives, the available space is the capacity
89 of a single drive, and the set protects against a failure of (N - 1)
92 Information about Software RAID on Linux is contained in the
93 Software-RAID mini-HOWTO, available from
94 <http://www.tldp.org/docs.html#howto>. There you will also
95 learn where to get the supporting user space utilities raidtools.
97 If you want to use such a RAID-1 set, say Y. To compile this code
98 as a module, choose M here: the module will be called raid1.
103 tristate "RAID-10 (mirrored striping) mode"
104 depends on BLK_DEV_MD
106 RAID-10 provides a combination of striping (RAID-0) and
107 mirroring (RAID-1) with easier configuration and more flexible
109 Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
110 be the same size (or at least, only as much as the smallest device
112 RAID-10 provides a variety of layouts that provide different levels
113 of redundancy and performance.
115 RAID-10 requires mdadm-1.7.0 or later, available at:
117 ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
122 tristate "RAID-4/RAID-5/RAID-6 mode"
123 depends on BLK_DEV_MD
128 select ASYNC_RAID6_RECOV
130 A RAID-5 set of N drives with a capacity of C MB per drive provides
131 the capacity of C * (N - 1) MB, and protects against a failure
132 of a single drive. For a given sector (row) number, (N - 1) drives
133 contain data sectors, and one drive contains the parity protection.
134 For a RAID-4 set, the parity blocks are present on a single drive,
135 while a RAID-5 set distributes the parity across the drives in one
136 of the available parity distribution methods.
138 A RAID-6 set of N drives with a capacity of C MB per drive
139 provides the capacity of C * (N - 2) MB, and protects
140 against a failure of any two drives. For a given sector
141 (row) number, (N - 2) drives contain data sectors, and two
142 drives contains two independent redundancy syndromes. Like
143 RAID-5, RAID-6 distributes the syndromes across the drives
144 in one of the available parity distribution methods.
146 Information about Software RAID on Linux is contained in the
147 Software-RAID mini-HOWTO, available from
148 <http://www.tldp.org/docs.html#howto>. There you will also
149 learn where to get the supporting user space utilities raidtools.
151 If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
152 compile this code as a module, choose M here: the module
153 will be called raid456.
157 config MULTICORE_RAID456
158 bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
159 depends on MD_RAID456
161 depends on EXPERIMENTAL
163 Enable the raid456 module to dispatch per-stripe raid operations to a
169 tristate "Multipath I/O support"
170 depends on BLK_DEV_MD
172 MD_MULTIPATH provides a simple multi-path personality for use
173 the MD framework. It is not under active development. New
174 projects should consider using DM_MULTIPATH which has more
175 features and more testing.
180 tristate "Faulty test module for MD"
181 depends on BLK_DEV_MD
183 The "faulty" module allows for a block device that occasionally returns
184 read or write errors. It is useful for testing.
189 tristate "Device mapper support"
191 Device-mapper is a low level volume manager. It works by allowing
192 people to specify mappings for ranges of logical sectors. Various
193 mapping types are available, in addition people may write their own
194 modules containing custom mappings if they wish.
196 Higher level volume managers such as LVM2 use this driver.
198 To compile this as a module, choose M here: the module will be
204 boolean "Device mapper debugging support"
205 depends on BLK_DEV_DM
207 Enable this for messages that may help debug device-mapper problems.
213 depends on BLK_DEV_DM && EXPERIMENTAL
215 This interface allows you to do buffered I/O on a device and acts
216 as a cache, holding recently-read blocks in memory and performing
220 tristate "Crypt target support"
221 depends on BLK_DEV_DM
225 This device-mapper target allows you to create a device that
226 transparently encrypts the data on it. You'll need to activate
227 the ciphers you're going to use in the cryptoapi configuration.
229 Information on how to use dm-crypt can be found on
231 <http://www.saout.de/misc/dm-crypt/>
233 To compile this code as a module, choose M here: the module will
239 tristate "Snapshot target"
240 depends on BLK_DEV_DM
242 Allow volume managers to take writable snapshots of a device.
245 tristate "Mirror target"
246 depends on BLK_DEV_DM
248 Allow volume managers to mirror logical volumes, also
249 needed for live data migration tools such as 'pvmove'.
252 tristate "RAID 1/4/5/6 target (EXPERIMENTAL)"
253 depends on BLK_DEV_DM && EXPERIMENTAL
258 A dm target that supports RAID1, RAID4, RAID5 and RAID6 mappings
260 A RAID-5 set of N drives with a capacity of C MB per drive provides
261 the capacity of C * (N - 1) MB, and protects against a failure
262 of a single drive. For a given sector (row) number, (N - 1) drives
263 contain data sectors, and one drive contains the parity protection.
264 For a RAID-4 set, the parity blocks are present on a single drive,
265 while a RAID-5 set distributes the parity across the drives in one
266 of the available parity distribution methods.
268 A RAID-6 set of N drives with a capacity of C MB per drive
269 provides the capacity of C * (N - 2) MB, and protects
270 against a failure of any two drives. For a given sector
271 (row) number, (N - 2) drives contain data sectors, and two
272 drives contains two independent redundancy syndromes. Like
273 RAID-5, RAID-6 distributes the syndromes across the drives
274 in one of the available parity distribution methods.
276 config DM_LOG_USERSPACE
277 tristate "Mirror userspace logging (EXPERIMENTAL)"
278 depends on DM_MIRROR && EXPERIMENTAL && NET
281 The userspace logging module provides a mechanism for
282 relaying the dm-dirty-log API to userspace. Log designs
283 which are more suited to userspace implementation (e.g.
284 shared storage logs) or experimental logs can be implemented
285 by leveraging this framework.
288 tristate "Zero target"
289 depends on BLK_DEV_DM
291 A target that discards writes, and returns all zeroes for
292 reads. Useful in some recovery situations.
295 tristate "Multipath target"
296 depends on BLK_DEV_DM
297 # nasty syntax but means make DM_MULTIPATH independent
298 # of SCSI_DH if the latter isn't defined but if
299 # it is, DM_MULTIPATH must depend on it. We get a build
300 # error if SCSI_DH=m and DM_MULTIPATH=y
301 depends on SCSI_DH || !SCSI_DH
303 Allow volume managers to support multipath hardware.
305 config DM_MULTIPATH_QL
306 tristate "I/O Path Selector based on the number of in-flight I/Os"
307 depends on DM_MULTIPATH
309 This path selector is a dynamic load balancer which selects
310 the path with the least number of in-flight I/Os.
314 config DM_MULTIPATH_ST
315 tristate "I/O Path Selector based on the service time"
316 depends on DM_MULTIPATH
318 This path selector is a dynamic load balancer which selects
319 the path expected to complete the incoming I/O in the shortest
325 tristate "I/O delaying target (EXPERIMENTAL)"
326 depends on BLK_DEV_DM && EXPERIMENTAL
328 A target that delays reads and/or writes and can send
329 them to different devices. Useful for testing.
334 bool "DM uevents (EXPERIMENTAL)"
335 depends on BLK_DEV_DM && EXPERIMENTAL
337 Generate udev events for DM events.
340 tristate "Flakey target (EXPERIMENTAL)"
341 depends on BLK_DEV_DM && EXPERIMENTAL
343 A target that intermittently fails I/O for debugging purposes.