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_LINEAR 34 tristate "Linear (append) mode" 35 depends on BLK_DEV_MD 36 ---help--- 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. 40 41 To compile this as a module, choose M here: the module 42 will be called linear. 43 44 If unsure, say Y. 45 46config MD_RAID0 47 tristate "RAID-0 (striping) mode" 48 depends on BLK_DEV_MD 49 ---help--- 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. 55 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. 60 61 To compile this as a module, choose M here: the module 62 will be called raid0. 63 64 If unsure, say Y. 65 66config MD_RAID1 67 tristate "RAID-1 (mirroring) mode" 68 depends on BLK_DEV_MD 69 ---help--- 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) 76 drives. 77 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. 82 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. 85 86 If unsure, say Y. 87 88config MD_RAID10 89 tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)" 90 depends on BLK_DEV_MD && EXPERIMENTAL 91 ---help--- 92 RAID-10 provides a combination of striping (RAID-0) and 93 mirroring (RAID-1) with easier configuration and more flexible 94 layout. 95 Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to 96 be the same size (or at least, only as much as the smallest device 97 will be used). 98 RAID-10 provides a variety of layouts that provide different levels 99 of redundancy and performance. 100 101 RAID-10 requires mdadm-1.7.0 or later, available at: 102 103 ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/ 104 105 If unsure, say Y. 106 107config MD_RAID456 108 tristate "RAID-4/RAID-5/RAID-6 mode" 109 depends on BLK_DEV_MD 110 select ASYNC_MEMCPY 111 select ASYNC_XOR 112 ---help--- 113 A RAID-5 set of N drives with a capacity of C MB per drive provides 114 the capacity of C * (N - 1) MB, and protects against a failure 115 of a single drive. For a given sector (row) number, (N - 1) drives 116 contain data sectors, and one drive contains the parity protection. 117 For a RAID-4 set, the parity blocks are present on a single drive, 118 while a RAID-5 set distributes the parity across the drives in one 119 of the available parity distribution methods. 120 121 A RAID-6 set of N drives with a capacity of C MB per drive 122 provides the capacity of C * (N - 2) MB, and protects 123 against a failure of any two drives. For a given sector 124 (row) number, (N - 2) drives contain data sectors, and two 125 drives contains two independent redundancy syndromes. Like 126 RAID-5, RAID-6 distributes the syndromes across the drives 127 in one of the available parity distribution methods. 128 129 Information about Software RAID on Linux is contained in the 130 Software-RAID mini-HOWTO, available from 131 <http://www.tldp.org/docs.html#howto>. There you will also 132 learn where to get the supporting user space utilities raidtools. 133 134 If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To 135 compile this code as a module, choose M here: the module 136 will be called raid456. 137 138 If unsure, say Y. 139 140config MD_RAID5_RESHAPE 141 bool "Support adding drives to a raid-5 array" 142 depends on MD_RAID456 143 default y 144 ---help--- 145 A RAID-5 set can be expanded by adding extra drives. This 146 requires "restriping" the array which means (almost) every 147 block must be written to a different place. 148 149 This option allows such restriping to be done while the array 150 is online. 151 152 You will need mdadm version 2.4.1 or later to use this 153 feature safely. During the early stage of reshape there is 154 a critical section where live data is being over-written. A 155 crash during this time needs extra care for recovery. The 156 newer mdadm takes a copy of the data in the critical section 157 and will restore it, if necessary, after a crash. 158 159 The mdadm usage is e.g. 160 mdadm --grow /dev/md1 --raid-disks=6 161 to grow '/dev/md1' to having 6 disks. 162 163 Note: The array can only be expanded, not contracted. 164 There should be enough spares already present to make the new 165 array workable. 166 167 If unsure, say Y. 168 169config MD_MULTIPATH 170 tristate "Multipath I/O support" 171 depends on BLK_DEV_MD 172 help 173 Multipath-IO is the ability of certain devices to address the same 174 physical disk over multiple 'IO paths'. The code ensures that such 175 paths can be defined and handled at runtime, and ensures that a 176 transparent failover to the backup path(s) happens if a IO errors 177 arrives on the primary path. 178 179 If unsure, say N. 180 181config MD_FAULTY 182 tristate "Faulty test module for MD" 183 depends on BLK_DEV_MD 184 help 185 The "faulty" module allows for a block device that occasionally returns 186 read or write errors. It is useful for testing. 187 188 In unsure, say N. 189 190config BLK_DEV_DM 191 tristate "Device mapper support" 192 ---help--- 193 Device-mapper is a low level volume manager. It works by allowing 194 people to specify mappings for ranges of logical sectors. Various 195 mapping types are available, in addition people may write their own 196 modules containing custom mappings if they wish. 197 198 Higher level volume managers such as LVM2 use this driver. 199 200 To compile this as a module, choose M here: the module will be 201 called dm-mod. 202 203 If unsure, say N. 204 205config DM_DEBUG 206 boolean "Device mapper debugging support" 207 depends on BLK_DEV_DM 208 ---help--- 209 Enable this for messages that may help debug device-mapper problems. 210 211 If unsure, say N. 212 213config DM_CRYPT 214 tristate "Crypt target support" 215 depends on BLK_DEV_DM 216 select CRYPTO 217 select CRYPTO_CBC 218 ---help--- 219 This device-mapper target allows you to create a device that 220 transparently encrypts the data on it. You'll need to activate 221 the ciphers you're going to use in the cryptoapi configuration. 222 223 Information on how to use dm-crypt can be found on 224 225 <http://www.saout.de/misc/dm-crypt/> 226 227 To compile this code as a module, choose M here: the module will 228 be called dm-crypt. 229 230 If unsure, say N. 231 232config DM_SNAPSHOT 233 tristate "Snapshot target" 234 depends on BLK_DEV_DM 235 ---help--- 236 Allow volume managers to take writable snapshots of a device. 237 238config DM_MIRROR 239 tristate "Mirror target" 240 depends on BLK_DEV_DM 241 ---help--- 242 Allow volume managers to mirror logical volumes, also 243 needed for live data migration tools such as 'pvmove'. 244 245config DM_ZERO 246 tristate "Zero target" 247 depends on BLK_DEV_DM 248 ---help--- 249 A target that discards writes, and returns all zeroes for 250 reads. Useful in some recovery situations. 251 252config DM_MULTIPATH 253 tristate "Multipath target" 254 depends on BLK_DEV_DM 255 # nasty syntax but means make DM_MULTIPATH independent 256 # of SCSI_DH if the latter isn't defined but if 257 # it is, DM_MULTIPATH must depend on it. We get a build 258 # error if SCSI_DH=m and DM_MULTIPATH=y 259 depends on SCSI_DH || !SCSI_DH 260 ---help--- 261 Allow volume managers to support multipath hardware. 262 263config DM_DELAY 264 tristate "I/O delaying target (EXPERIMENTAL)" 265 depends on BLK_DEV_DM && EXPERIMENTAL 266 ---help--- 267 A target that delays reads and/or writes and can send 268 them to different devices. Useful for testing. 269 270 If unsure, say N. 271 272config DM_UEVENT 273 bool "DM uevents (EXPERIMENTAL)" 274 depends on BLK_DEV_DM && EXPERIMENTAL 275 ---help--- 276 Generate udev events for DM events. 277 278endif # MD 279