1# 2# Block device driver configuration 3# 4 5menuconfig MD 6 bool "Multiple devices driver support (RAID and LVM)" 7 depends on BLOCK 8 help 9 Support multiple physical spindles through a single logical device. 10 Required for RAID and logical volume management. 11 12if MD 13 14config BLK_DEV_MD 15 tristate "RAID support" 16 ---help--- 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. 25 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. 30 31 If unsure, say N. 32 33config MD_AUTODETECT 34 bool "Autodetect RAID arrays during kernel boot" 35 depends on BLK_DEV_MD=y 36 default y 37 ---help--- 38 If you say Y here, then the kernel will try to autodetect raid 39 arrays as part of its boot process. 40 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. 44 45 If unsure, say Y. 46 47config MD_LINEAR 48 tristate "Linear (append) mode" 49 depends on BLK_DEV_MD 50 ---help--- 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. 54 55 To compile this as a module, choose M here: the module 56 will be called linear. 57 58 If unsure, say Y. 59 60config MD_RAID0 61 tristate "RAID-0 (striping) mode" 62 depends on BLK_DEV_MD 63 ---help--- 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. 69 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. 74 75 To compile this as a module, choose M here: the module 76 will be called raid0. 77 78 If unsure, say Y. 79 80config MD_RAID1 81 tristate "RAID-1 (mirroring) mode" 82 depends on BLK_DEV_MD 83 ---help--- 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) 90 drives. 91 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. 96 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. 99 100 If unsure, say Y. 101 102config MD_RAID10 103 tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)" 104 depends on BLK_DEV_MD && EXPERIMENTAL 105 ---help--- 106 RAID-10 provides a combination of striping (RAID-0) and 107 mirroring (RAID-1) with easier configuration and more flexible 108 layout. 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 111 will be used). 112 RAID-10 provides a variety of layouts that provide different levels 113 of redundancy and performance. 114 115 RAID-10 requires mdadm-1.7.0 or later, available at: 116 117 ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/ 118 119 If unsure, say Y. 120 121config MD_RAID456 122 tristate "RAID-4/RAID-5/RAID-6 mode" 123 depends on BLK_DEV_MD 124 select ASYNC_MEMCPY 125 select ASYNC_XOR 126 ---help--- 127 A RAID-5 set of N drives with a capacity of C MB per drive provides 128 the capacity of C * (N - 1) MB, and protects against a failure 129 of a single drive. For a given sector (row) number, (N - 1) drives 130 contain data sectors, and one drive contains the parity protection. 131 For a RAID-4 set, the parity blocks are present on a single drive, 132 while a RAID-5 set distributes the parity across the drives in one 133 of the available parity distribution methods. 134 135 A RAID-6 set of N drives with a capacity of C MB per drive 136 provides the capacity of C * (N - 2) MB, and protects 137 against a failure of any two drives. For a given sector 138 (row) number, (N - 2) drives contain data sectors, and two 139 drives contains two independent redundancy syndromes. Like 140 RAID-5, RAID-6 distributes the syndromes across the drives 141 in one of the available parity distribution methods. 142 143 Information about Software RAID on Linux is contained in the 144 Software-RAID mini-HOWTO, available from 145 <http://www.tldp.org/docs.html#howto>. There you will also 146 learn where to get the supporting user space utilities raidtools. 147 148 If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To 149 compile this code as a module, choose M here: the module 150 will be called raid456. 151 152 If unsure, say Y. 153 154config MD_RAID5_RESHAPE 155 bool "Support adding drives to a raid-5 array" 156 depends on MD_RAID456 157 default y 158 ---help--- 159 A RAID-5 set can be expanded by adding extra drives. This 160 requires "restriping" the array which means (almost) every 161 block must be written to a different place. 162 163 This option allows such restriping to be done while the array 164 is online. 165 166 You will need mdadm version 2.4.1 or later to use this 167 feature safely. During the early stage of reshape there is 168 a critical section where live data is being over-written. A 169 crash during this time needs extra care for recovery. The 170 newer mdadm takes a copy of the data in the critical section 171 and will restore it, if necessary, after a crash. 172 173 The mdadm usage is e.g. 174 mdadm --grow /dev/md1 --raid-disks=6 175 to grow '/dev/md1' to having 6 disks. 176 177 Note: The array can only be expanded, not contracted. 178 There should be enough spares already present to make the new 179 array workable. 180 181 If unsure, say Y. 182 183config MD_MULTIPATH 184 tristate "Multipath I/O support" 185 depends on BLK_DEV_MD 186 help 187 Multipath-IO is the ability of certain devices to address the same 188 physical disk over multiple 'IO paths'. The code ensures that such 189 paths can be defined and handled at runtime, and ensures that a 190 transparent failover to the backup path(s) happens if a IO errors 191 arrives on the primary path. 192 193 If unsure, say N. 194 195config MD_FAULTY 196 tristate "Faulty test module for MD" 197 depends on BLK_DEV_MD 198 help 199 The "faulty" module allows for a block device that occasionally returns 200 read or write errors. It is useful for testing. 201 202 In unsure, say N. 203 204config BLK_DEV_DM 205 tristate "Device mapper support" 206 ---help--- 207 Device-mapper is a low level volume manager. It works by allowing 208 people to specify mappings for ranges of logical sectors. Various 209 mapping types are available, in addition people may write their own 210 modules containing custom mappings if they wish. 211 212 Higher level volume managers such as LVM2 use this driver. 213 214 To compile this as a module, choose M here: the module will be 215 called dm-mod. 216 217 If unsure, say N. 218 219config DM_DEBUG 220 boolean "Device mapper debugging support" 221 depends on BLK_DEV_DM 222 ---help--- 223 Enable this for messages that may help debug device-mapper problems. 224 225 If unsure, say N. 226 227config DM_CRYPT 228 tristate "Crypt target support" 229 depends on BLK_DEV_DM 230 select CRYPTO 231 select CRYPTO_CBC 232 ---help--- 233 This device-mapper target allows you to create a device that 234 transparently encrypts the data on it. You'll need to activate 235 the ciphers you're going to use in the cryptoapi configuration. 236 237 Information on how to use dm-crypt can be found on 238 239 <http://www.saout.de/misc/dm-crypt/> 240 241 To compile this code as a module, choose M here: the module will 242 be called dm-crypt. 243 244 If unsure, say N. 245 246config DM_SNAPSHOT 247 tristate "Snapshot target" 248 depends on BLK_DEV_DM 249 ---help--- 250 Allow volume managers to take writable snapshots of a device. 251 252config DM_MIRROR 253 tristate "Mirror target" 254 depends on BLK_DEV_DM 255 ---help--- 256 Allow volume managers to mirror logical volumes, also 257 needed for live data migration tools such as 'pvmove'. 258 259config DM_ZERO 260 tristate "Zero target" 261 depends on BLK_DEV_DM 262 ---help--- 263 A target that discards writes, and returns all zeroes for 264 reads. Useful in some recovery situations. 265 266config DM_MULTIPATH 267 tristate "Multipath target" 268 depends on BLK_DEV_DM 269 # nasty syntax but means make DM_MULTIPATH independent 270 # of SCSI_DH if the latter isn't defined but if 271 # it is, DM_MULTIPATH must depend on it. We get a build 272 # error if SCSI_DH=m and DM_MULTIPATH=y 273 depends on SCSI_DH || !SCSI_DH 274 ---help--- 275 Allow volume managers to support multipath hardware. 276 277config DM_DELAY 278 tristate "I/O delaying target (EXPERIMENTAL)" 279 depends on BLK_DEV_DM && EXPERIMENTAL 280 ---help--- 281 A target that delays reads and/or writes and can send 282 them to different devices. Useful for testing. 283 284 If unsure, say N. 285 286config DM_UEVENT 287 bool "DM uevents (EXPERIMENTAL)" 288 depends on BLK_DEV_DM && EXPERIMENTAL 289 ---help--- 290 Generate udev events for DM events. 291 292endif # MD 293