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 (EXPERIMENTAL)"
104 depends on BLK_DEV_MD && EXPERIMENTAL
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.
160 config ASYNC_RAID6_TEST
161 tristate "Self test for hardware accelerated raid6 recovery"
162 depends on MD_RAID6_PQ
163 select ASYNC_RAID6_RECOV
165 This is a one-shot self test that permutes through the
166 recovery of all the possible two disk failure scenarios for a
167 N-disk array. Recovery is performed with the asynchronous
168 raid6 recovery routines, and will optionally use an offload
169 engine if one is available.
174 tristate "Multipath I/O support"
175 depends on BLK_DEV_MD
177 Multipath-IO is the ability of certain devices to address the same
178 physical disk over multiple 'IO paths'. The code ensures that such
179 paths can be defined and handled at runtime, and ensures that a
180 transparent failover to the backup path(s) happens if a IO errors
181 arrives on the primary path.
186 tristate "Faulty test module for MD"
187 depends on BLK_DEV_MD
189 The "faulty" module allows for a block device that occasionally returns
190 read or write errors. It is useful for testing.
195 tristate "Device mapper support"
197 Device-mapper is a low level volume manager. It works by allowing
198 people to specify mappings for ranges of logical sectors. Various
199 mapping types are available, in addition people may write their own
200 modules containing custom mappings if they wish.
202 Higher level volume managers such as LVM2 use this driver.
204 To compile this as a module, choose M here: the module will be
210 boolean "Device mapper debugging support"
211 depends on BLK_DEV_DM
213 Enable this for messages that may help debug device-mapper problems.
218 tristate "Crypt target support"
219 depends on BLK_DEV_DM
223 This device-mapper target allows you to create a device that
224 transparently encrypts the data on it. You'll need to activate
225 the ciphers you're going to use in the cryptoapi configuration.
227 Information on how to use dm-crypt can be found on
229 <http://www.saout.de/misc/dm-crypt/>
231 To compile this code as a module, choose M here: the module will
237 tristate "Snapshot target"
238 depends on BLK_DEV_DM
240 Allow volume managers to take writable snapshots of a device.
243 tristate "Mirror target"
244 depends on BLK_DEV_DM
246 Allow volume managers to mirror logical volumes, also
247 needed for live data migration tools such as 'pvmove'.
250 tristate "Zero target"
251 depends on BLK_DEV_DM
253 A target that discards writes, and returns all zeroes for
254 reads. Useful in some recovery situations.
257 tristate "Multipath target"
258 depends on BLK_DEV_DM
259 # nasty syntax but means make DM_MULTIPATH independent
260 # of SCSI_DH if the latter isn't defined but if
261 # it is, DM_MULTIPATH must depend on it. We get a build
262 # error if SCSI_DH=m and DM_MULTIPATH=y
263 depends on SCSI_DH || !SCSI_DH
265 Allow volume managers to support multipath hardware.
268 tristate "I/O delaying target (EXPERIMENTAL)"
269 depends on BLK_DEV_DM && EXPERIMENTAL
271 A target that delays reads and/or writes and can send
272 them to different devices. Useful for testing.
277 bool "DM uevents (EXPERIMENTAL)"
278 depends on BLK_DEV_DM && EXPERIMENTAL
280 Generate udev events for DM events.