2 # Block device driver configuration
5 menu "Multi-device support (RAID and LVM)"
8 bool "Multiple devices driver support (RAID and LVM)"
10 Support multiple physical spindles through a single logical device.
11 Required for RAID and logical volume management.
14 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 tristate "Linear (append) mode"
37 If you say Y here, then your multiple devices driver will be able to
38 use the so-called linear mode, i.e. it will combine the hard disk
39 partitions by simply appending one to the other.
41 To compile this as a module, choose M here: the module
42 will be called linear.
47 tristate "RAID-0 (striping) mode"
50 If you say Y here, then your multiple devices driver will be able to
51 use the so-called raid0 mode, i.e. it will combine the hard disk
52 partitions into one logical device in such a fashion as to fill them
53 up evenly, one chunk here and one chunk there. This will increase
54 the throughput rate if the partitions reside on distinct disks.
56 Information about Software RAID on Linux is contained in the
57 Software-RAID mini-HOWTO, available from
58 <http://www.tldp.org/docs.html#howto>. There you will also
59 learn where to get the supporting user space utilities raidtools.
61 To compile this as a module, choose M here: the module
67 tristate "RAID-1 (mirroring) mode"
70 A RAID-1 set consists of several disk drives which are exact copies
71 of each other. In the event of a mirror failure, the RAID driver
72 will continue to use the operational mirrors in the set, providing
73 an error free MD (multiple device) to the higher levels of the
74 kernel. In a set with N drives, the available space is the capacity
75 of a single drive, and the set protects against a failure of (N - 1)
78 Information about Software RAID on Linux is contained in the
79 Software-RAID mini-HOWTO, available from
80 <http://www.tldp.org/docs.html#howto>. There you will also
81 learn where to get the supporting user space utilities raidtools.
83 If you want to use such a RAID-1 set, say Y. To compile this code
84 as a module, choose M here: the module will be called raid1.
89 tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
90 depends on BLK_DEV_MD && EXPERIMENTAL
92 RAID-10 provides a combination of striping (RAID-0) and
93 mirroring (RAID-1) with easier configuration and more flexable
95 Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
96 be the same size (or atleast, only as much as the smallest device
98 RAID-10 provides a variety of layouts that provide different levels
99 of redundancy and performance.
101 RAID-10 requires mdadm-1.7.0 or later, available at:
103 ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
107 tristate "RAID-4/RAID-5 mode"
108 depends on BLK_DEV_MD
110 A RAID-5 set of N drives with a capacity of C MB per drive provides
111 the capacity of C * (N - 1) MB, and protects against a failure
112 of a single drive. For a given sector (row) number, (N - 1) drives
113 contain data sectors, and one drive contains the parity protection.
114 For a RAID-4 set, the parity blocks are present on a single drive,
115 while a RAID-5 set distributes the parity across the drives in one
116 of the available parity distribution methods.
118 Information about Software RAID on Linux is contained in the
119 Software-RAID mini-HOWTO, available from
120 <http://www.tldp.org/docs.html#howto>. There you will also
121 learn where to get the supporting user space utilities raidtools.
123 If you want to use such a RAID-4/RAID-5 set, say Y. To compile
124 this code as a module, choose M here: the module will be called raid5.
129 tristate "RAID-6 mode (EXPERIMENTAL)"
130 depends on BLK_DEV_MD && EXPERIMENTAL
132 WARNING: RAID-6 is currently highly experimental. If you
133 use it, there is no guarantee whatsoever that it won't
134 destroy your data, eat your disk drives, insult your mother,
135 or re-appoint George W. Bush.
137 A RAID-6 set of N drives with a capacity of C MB per drive
138 provides the capacity of C * (N - 2) MB, and protects
139 against a failure of any two drives. For a given sector
140 (row) number, (N - 2) drives contain data sectors, and two
141 drives contains two independent redundancy syndromes. Like
142 RAID-5, RAID-6 distributes the syndromes across the drives
143 in one of the available parity distribution methods.
145 RAID-6 requires mdadm-1.5.0 or later, available at:
147 ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
149 If you want to use such a RAID-6 set, say Y. To compile
150 this code as a module, choose M here: the module will be
156 tristate "Multipath I/O support"
157 depends on BLK_DEV_MD
159 Multipath-IO is the ability of certain devices to address the same
160 physical disk over multiple 'IO paths'. The code ensures that such
161 paths can be defined and handled at runtime, and ensures that a
162 transparent failover to the backup path(s) happens if a IO errors
163 arrives on the primary path.
168 tristate "Device mapper support"
171 Device-mapper is a low level volume manager. It works by allowing
172 people to specify mappings for ranges of logical sectors. Various
173 mapping types are available, in addition people may write their own
174 modules containing custom mappings if they wish.
176 Higher level volume managers such as LVM2 use this driver.
178 To compile this as a module, choose M here: the module will be
184 tristate "Crypt target support"
185 depends on BLK_DEV_DM && EXPERIMENTAL
188 This device-mapper target allows you to create a device that
189 transparently encrypts the data on it. You'll need to activate
190 the ciphers you're going to use in the cryptoapi configuration.
192 Information on how to use dm-crypt can be found on
194 http://www.saout.de/misc/dm-crypt/
196 To compile this code as a module, choose M here: the module will
202 tristate "Snapshot target (EXPERIMENTAL)"
203 depends on BLK_DEV_DM && EXPERIMENTAL
205 Allow volume managers to take writeable snapshots of a device.
208 tristate "Mirror target (EXPERIMENTAL)"
209 depends on BLK_DEV_DM && EXPERIMENTAL
211 Allow volume managers to mirror logical volumes, also
212 needed for live data migration tools such as 'pvmove'.
215 tristate "Zero target (EXPERIMENTAL)"
216 depends on BLK_DEV_DM && EXPERIMENTAL
218 A target that discards writes, and returns all zeroes for
219 reads. Useful in some recovery situations.