1# 2# Block device driver configuration 3# 4 5menu "Multi-device support (RAID and LVM)" 6 7config MD 8 bool "Multiple devices driver support (RAID and LVM)" 9 help 10 Support multiple physical spindles through a single logical device. 11 Required for RAID and logical volume management. 12 13config BLK_DEV_MD 14 tristate "RAID support" 15 depends on MD 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 ---help--- 111 A RAID-5 set of N drives with a capacity of C MB per drive provides 112 the capacity of C * (N - 1) MB, and protects against a failure 113 of a single drive. For a given sector (row) number, (N - 1) drives 114 contain data sectors, and one drive contains the parity protection. 115 For a RAID-4 set, the parity blocks are present on a single drive, 116 while a RAID-5 set distributes the parity across the drives in one 117 of the available parity distribution methods. 118 119 A RAID-6 set of N drives with a capacity of C MB per drive 120 provides the capacity of C * (N - 2) MB, and protects 121 against a failure of any two drives. For a given sector 122 (row) number, (N - 2) drives contain data sectors, and two 123 drives contains two independent redundancy syndromes. Like 124 RAID-5, RAID-6 distributes the syndromes across the drives 125 in one of the available parity distribution methods. 126 127 Information about Software RAID on Linux is contained in the 128 Software-RAID mini-HOWTO, available from 129 <http://www.tldp.org/docs.html#howto>. There you will also 130 learn where to get the supporting user space utilities raidtools. 131 132 If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To 133 compile this code as a module, choose M here: the module 134 will be called raid456. 135 136 If unsure, say Y. 137 138config MD_RAID5_RESHAPE 139 bool "Support adding drives to a raid-5 array (experimental)" 140 depends on MD_RAID456 && EXPERIMENTAL 141 ---help--- 142 A RAID-5 set can be expanded by adding extra drives. This 143 requires "restriping" the array which means (almost) every 144 block must be written to a different place. 145 146 This option allows such restriping to be done while the array 147 is online. However it is still EXPERIMENTAL code. It should 148 work, but please be sure that you have backups. 149 150 You will need mdadm version 2.4.1 or later to use this 151 feature safely. During the early stage of reshape there is 152 a critical section where live data is being over-written. A 153 crash during this time needs extra care for recovery. The 154 newer mdadm takes a copy of the data in the critical section 155 and will restore it, if necessary, after a crash. 156 157 The mdadm usage is e.g. 158 mdadm --grow /dev/md1 --raid-disks=6 159 to grow '/dev/md1' to having 6 disks. 160 161 Note: The array can only be expanded, not contracted. 162 There should be enough spares already present to make the new 163 array workable. 164 165config MD_MULTIPATH 166 tristate "Multipath I/O support" 167 depends on BLK_DEV_MD 168 help 169 Multipath-IO is the ability of certain devices to address the same 170 physical disk over multiple 'IO paths'. The code ensures that such 171 paths can be defined and handled at runtime, and ensures that a 172 transparent failover to the backup path(s) happens if a IO errors 173 arrives on the primary path. 174 175 If unsure, say N. 176 177config MD_FAULTY 178 tristate "Faulty test module for MD" 179 depends on BLK_DEV_MD 180 help 181 The "faulty" module allows for a block device that occasionally returns 182 read or write errors. It is useful for testing. 183 184 In unsure, say N. 185 186config BLK_DEV_DM 187 tristate "Device mapper support" 188 depends on MD 189 ---help--- 190 Device-mapper is a low level volume manager. It works by allowing 191 people to specify mappings for ranges of logical sectors. Various 192 mapping types are available, in addition people may write their own 193 modules containing custom mappings if they wish. 194 195 Higher level volume managers such as LVM2 use this driver. 196 197 To compile this as a module, choose M here: the module will be 198 called dm-mod. 199 200 If unsure, say N. 201 202config DM_CRYPT 203 tristate "Crypt target support" 204 depends on BLK_DEV_DM && EXPERIMENTAL 205 select CRYPTO 206 ---help--- 207 This device-mapper target allows you to create a device that 208 transparently encrypts the data on it. You'll need to activate 209 the ciphers you're going to use in the cryptoapi configuration. 210 211 Information on how to use dm-crypt can be found on 212 213 <http://www.saout.de/misc/dm-crypt/> 214 215 To compile this code as a module, choose M here: the module will 216 be called dm-crypt. 217 218 If unsure, say N. 219 220config DM_SNAPSHOT 221 tristate "Snapshot target (EXPERIMENTAL)" 222 depends on BLK_DEV_DM && EXPERIMENTAL 223 ---help--- 224 Allow volume managers to take writable snapshots of a device. 225 226config DM_MIRROR 227 tristate "Mirror target (EXPERIMENTAL)" 228 depends on BLK_DEV_DM && EXPERIMENTAL 229 ---help--- 230 Allow volume managers to mirror logical volumes, also 231 needed for live data migration tools such as 'pvmove'. 232 233config DM_ZERO 234 tristate "Zero target (EXPERIMENTAL)" 235 depends on BLK_DEV_DM && EXPERIMENTAL 236 ---help--- 237 A target that discards writes, and returns all zeroes for 238 reads. Useful in some recovery situations. 239 240config DM_MULTIPATH 241 tristate "Multipath target (EXPERIMENTAL)" 242 depends on BLK_DEV_DM && EXPERIMENTAL 243 ---help--- 244 Allow volume managers to support multipath hardware. 245 246config DM_MULTIPATH_EMC 247 tristate "EMC CX/AX multipath support (EXPERIMENTAL)" 248 depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL 249 ---help--- 250 Multipath support for EMC CX/AX series hardware. 251 252endmenu 253 254