2 # Block device driver configuration
7 menu "Multi-device support (RAID and LVM)"
10 bool "Multiple devices driver support (RAID and LVM)"
12 Support multiple physical spindles through a single logical device.
13 Required for RAID and logical volume management.
16 tristate "RAID support"
19 This driver lets you combine several hard disk partitions into one
20 logical block device. This can be used to simply append one
21 partition to another one or to combine several redundant hard disks
22 into a RAID1/4/5 device so as to provide protection against hard
23 disk failures. This is called "Software RAID" since the combining of
24 the partitions is done by the kernel. "Hardware RAID" means that the
25 combining is done by a dedicated controller; if you have such a
26 controller, you do not need to say Y here.
28 More information about Software RAID on Linux is contained in the
29 Software RAID mini-HOWTO, available from
30 <http://www.tldp.org/docs.html#howto>. There you will also learn
31 where to get the supporting user space utilities raidtools.
36 tristate "Linear (append) mode"
39 If you say Y here, then your multiple devices driver will be able to
40 use the so-called linear mode, i.e. it will combine the hard disk
41 partitions by simply appending one to the other.
43 To compile this as a module, choose M here: the module
44 will be called linear.
49 tristate "RAID-0 (striping) mode"
52 If you say Y here, then your multiple devices driver will be able to
53 use the so-called raid0 mode, i.e. it will combine the hard disk
54 partitions into one logical device in such a fashion as to fill them
55 up evenly, one chunk here and one chunk there. This will increase
56 the throughput rate if the partitions reside on distinct disks.
58 Information about Software RAID on Linux is contained in the
59 Software-RAID mini-HOWTO, available from
60 <http://www.tldp.org/docs.html#howto>. There you will also
61 learn where to get the supporting user space utilities raidtools.
63 To compile this as a module, choose M here: the module
69 tristate "RAID-1 (mirroring) mode"
72 A RAID-1 set consists of several disk drives which are exact copies
73 of each other. In the event of a mirror failure, the RAID driver
74 will continue to use the operational mirrors in the set, providing
75 an error free MD (multiple device) to the higher levels of the
76 kernel. In a set with N drives, the available space is the capacity
77 of a single drive, and the set protects against a failure of (N - 1)
80 Information about Software RAID on Linux is contained in the
81 Software-RAID mini-HOWTO, available from
82 <http://www.tldp.org/docs.html#howto>. There you will also
83 learn where to get the supporting user space utilities raidtools.
85 If you want to use such a RAID-1 set, say Y. To compile this code
86 as a module, choose M here: the module will be called raid1.
91 tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
92 depends on BLK_DEV_MD && EXPERIMENTAL
94 RAID-10 provides a combination of striping (RAID-0) and
95 mirroring (RAID-1) with easier configuration and more flexible
97 Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
98 be the same size (or at least, only as much as the smallest device
100 RAID-10 provides a variety of layouts that provide different levels
101 of redundancy and performance.
103 RAID-10 requires mdadm-1.7.0 or later, available at:
105 ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
110 tristate "RAID-4/RAID-5/RAID-6 mode"
111 depends on BLK_DEV_MD
114 A RAID-5 set of N drives with a capacity of C MB per drive provides
115 the capacity of C * (N - 1) MB, and protects against a failure
116 of a single drive. For a given sector (row) number, (N - 1) drives
117 contain data sectors, and one drive contains the parity protection.
118 For a RAID-4 set, the parity blocks are present on a single drive,
119 while a RAID-5 set distributes the parity across the drives in one
120 of the available parity distribution methods.
122 A RAID-6 set of N drives with a capacity of C MB per drive
123 provides the capacity of C * (N - 2) MB, and protects
124 against a failure of any two drives. For a given sector
125 (row) number, (N - 2) drives contain data sectors, and two
126 drives contains two independent redundancy syndromes. Like
127 RAID-5, RAID-6 distributes the syndromes across the drives
128 in one of the available parity distribution methods.
130 Information about Software RAID on Linux is contained in the
131 Software-RAID mini-HOWTO, available from
132 <http://www.tldp.org/docs.html#howto>. There you will also
133 learn where to get the supporting user space utilities raidtools.
135 If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
136 compile this code as a module, choose M here: the module
137 will be called raid456.
141 config MD_RAID5_RESHAPE
142 bool "Support adding drives to a raid-5 array"
143 depends on MD_RAID456
146 A RAID-5 set can be expanded by adding extra drives. This
147 requires "restriping" the array which means (almost) every
148 block must be written to a different place.
150 This option allows such restriping to be done while the array
153 You will need mdadm version 2.4.1 or later to use this
154 feature safely. During the early stage of reshape there is
155 a critical section where live data is being over-written. A
156 crash during this time needs extra care for recovery. The
157 newer mdadm takes a copy of the data in the critical section
158 and will restore it, if necessary, after a crash.
160 The mdadm usage is e.g.
161 mdadm --grow /dev/md1 --raid-disks=6
162 to grow '/dev/md1' to having 6 disks.
164 Note: The array can only be expanded, not contracted.
165 There should be enough spares already present to make the new
171 tristate "Multipath I/O support"
172 depends on BLK_DEV_MD
174 Multipath-IO is the ability of certain devices to address the same
175 physical disk over multiple 'IO paths'. The code ensures that such
176 paths can be defined and handled at runtime, and ensures that a
177 transparent failover to the backup path(s) happens if a IO errors
178 arrives on the primary path.
183 tristate "Faulty test module for MD"
184 depends on BLK_DEV_MD
186 The "faulty" module allows for a block device that occasionally returns
187 read or write errors. It is useful for testing.
192 tristate "Device mapper support"
195 Device-mapper is a low level volume manager. It works by allowing
196 people to specify mappings for ranges of logical sectors. Various
197 mapping types are available, in addition people may write their own
198 modules containing custom mappings if they wish.
200 Higher level volume managers such as LVM2 use this driver.
202 To compile this as a module, choose M here: the module will be
208 boolean "Device mapper debugging support"
209 depends on BLK_DEV_DM && EXPERIMENTAL
211 Enable this for messages that may help debug device-mapper problems.
216 tristate "Crypt target support"
217 depends on BLK_DEV_DM && EXPERIMENTAL
221 This device-mapper target allows you to create a device that
222 transparently encrypts the data on it. You'll need to activate
223 the ciphers you're going to use in the cryptoapi configuration.
225 Information on how to use dm-crypt can be found on
227 <http://www.saout.de/misc/dm-crypt/>
229 To compile this code as a module, choose M here: the module will
235 tristate "Snapshot target (EXPERIMENTAL)"
236 depends on BLK_DEV_DM && EXPERIMENTAL
238 Allow volume managers to take writable snapshots of a device.
241 tristate "Mirror target (EXPERIMENTAL)"
242 depends on BLK_DEV_DM && EXPERIMENTAL
244 Allow volume managers to mirror logical volumes, also
245 needed for live data migration tools such as 'pvmove'.
248 tristate "Zero target (EXPERIMENTAL)"
249 depends on BLK_DEV_DM && EXPERIMENTAL
251 A target that discards writes, and returns all zeroes for
252 reads. Useful in some recovery situations.
255 tristate "Multipath target (EXPERIMENTAL)"
256 depends on BLK_DEV_DM && EXPERIMENTAL
258 Allow volume managers to support multipath hardware.
260 config DM_MULTIPATH_EMC
261 tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
262 depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
264 Multipath support for EMC CX/AX series hardware.
267 tristate "I/O delaying target (EXPERIMENTAL)"
268 depends on BLK_DEV_DM && EXPERIMENTAL
270 A target that delays reads and/or writes and can send
271 them to different devices. Useful for testing.