11da177e4SLinus Torvalds# 21da177e4SLinus Torvalds# Block device driver configuration 31da177e4SLinus Torvalds# 41da177e4SLinus Torvalds 59361401eSDavid Howellsif BLOCK 69361401eSDavid Howells 71da177e4SLinus Torvaldsmenu "Multi-device support (RAID and LVM)" 81da177e4SLinus Torvalds 91da177e4SLinus Torvaldsconfig MD 101da177e4SLinus Torvalds bool "Multiple devices driver support (RAID and LVM)" 111da177e4SLinus Torvalds help 121da177e4SLinus Torvalds Support multiple physical spindles through a single logical device. 131da177e4SLinus Torvalds Required for RAID and logical volume management. 141da177e4SLinus Torvalds 151da177e4SLinus Torvaldsconfig BLK_DEV_MD 161da177e4SLinus Torvalds tristate "RAID support" 171da177e4SLinus Torvalds depends on MD 181da177e4SLinus Torvalds ---help--- 191da177e4SLinus Torvalds This driver lets you combine several hard disk partitions into one 201da177e4SLinus Torvalds logical block device. This can be used to simply append one 211da177e4SLinus Torvalds partition to another one or to combine several redundant hard disks 221da177e4SLinus Torvalds into a RAID1/4/5 device so as to provide protection against hard 231da177e4SLinus Torvalds disk failures. This is called "Software RAID" since the combining of 241da177e4SLinus Torvalds the partitions is done by the kernel. "Hardware RAID" means that the 251da177e4SLinus Torvalds combining is done by a dedicated controller; if you have such a 261da177e4SLinus Torvalds controller, you do not need to say Y here. 271da177e4SLinus Torvalds 281da177e4SLinus Torvalds More information about Software RAID on Linux is contained in the 291da177e4SLinus Torvalds Software RAID mini-HOWTO, available from 301da177e4SLinus Torvalds <http://www.tldp.org/docs.html#howto>. There you will also learn 311da177e4SLinus Torvalds where to get the supporting user space utilities raidtools. 321da177e4SLinus Torvalds 331da177e4SLinus Torvalds If unsure, say N. 341da177e4SLinus Torvalds 351da177e4SLinus Torvaldsconfig MD_LINEAR 361da177e4SLinus Torvalds tristate "Linear (append) mode" 371da177e4SLinus Torvalds depends on BLK_DEV_MD 381da177e4SLinus Torvalds ---help--- 391da177e4SLinus Torvalds If you say Y here, then your multiple devices driver will be able to 401da177e4SLinus Torvalds use the so-called linear mode, i.e. it will combine the hard disk 411da177e4SLinus Torvalds partitions by simply appending one to the other. 421da177e4SLinus Torvalds 431da177e4SLinus Torvalds To compile this as a module, choose M here: the module 441da177e4SLinus Torvalds will be called linear. 451da177e4SLinus Torvalds 461da177e4SLinus Torvalds If unsure, say Y. 471da177e4SLinus Torvalds 481da177e4SLinus Torvaldsconfig MD_RAID0 491da177e4SLinus Torvalds tristate "RAID-0 (striping) mode" 501da177e4SLinus Torvalds depends on BLK_DEV_MD 511da177e4SLinus Torvalds ---help--- 521da177e4SLinus Torvalds If you say Y here, then your multiple devices driver will be able to 531da177e4SLinus Torvalds use the so-called raid0 mode, i.e. it will combine the hard disk 541da177e4SLinus Torvalds partitions into one logical device in such a fashion as to fill them 551da177e4SLinus Torvalds up evenly, one chunk here and one chunk there. This will increase 561da177e4SLinus Torvalds the throughput rate if the partitions reside on distinct disks. 571da177e4SLinus Torvalds 581da177e4SLinus Torvalds Information about Software RAID on Linux is contained in the 591da177e4SLinus Torvalds Software-RAID mini-HOWTO, available from 601da177e4SLinus Torvalds <http://www.tldp.org/docs.html#howto>. There you will also 611da177e4SLinus Torvalds learn where to get the supporting user space utilities raidtools. 621da177e4SLinus Torvalds 631da177e4SLinus Torvalds To compile this as a module, choose M here: the module 641da177e4SLinus Torvalds will be called raid0. 651da177e4SLinus Torvalds 661da177e4SLinus Torvalds If unsure, say Y. 671da177e4SLinus Torvalds 681da177e4SLinus Torvaldsconfig MD_RAID1 691da177e4SLinus Torvalds tristate "RAID-1 (mirroring) mode" 701da177e4SLinus Torvalds depends on BLK_DEV_MD 711da177e4SLinus Torvalds ---help--- 721da177e4SLinus Torvalds A RAID-1 set consists of several disk drives which are exact copies 731da177e4SLinus Torvalds of each other. In the event of a mirror failure, the RAID driver 741da177e4SLinus Torvalds will continue to use the operational mirrors in the set, providing 751da177e4SLinus Torvalds an error free MD (multiple device) to the higher levels of the 761da177e4SLinus Torvalds kernel. In a set with N drives, the available space is the capacity 771da177e4SLinus Torvalds of a single drive, and the set protects against a failure of (N - 1) 781da177e4SLinus Torvalds drives. 791da177e4SLinus Torvalds 801da177e4SLinus Torvalds Information about Software RAID on Linux is contained in the 811da177e4SLinus Torvalds Software-RAID mini-HOWTO, available from 821da177e4SLinus Torvalds <http://www.tldp.org/docs.html#howto>. There you will also 831da177e4SLinus Torvalds learn where to get the supporting user space utilities raidtools. 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds If you want to use such a RAID-1 set, say Y. To compile this code 861da177e4SLinus Torvalds as a module, choose M here: the module will be called raid1. 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds If unsure, say Y. 891da177e4SLinus Torvalds 901da177e4SLinus Torvaldsconfig MD_RAID10 911da177e4SLinus Torvalds tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)" 921da177e4SLinus Torvalds depends on BLK_DEV_MD && EXPERIMENTAL 931da177e4SLinus Torvalds ---help--- 941da177e4SLinus Torvalds RAID-10 provides a combination of striping (RAID-0) and 954d2554d0SJustin Piszcz mirroring (RAID-1) with easier configuration and more flexible 961da177e4SLinus Torvalds layout. 971da177e4SLinus Torvalds Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to 981da177e4SLinus Torvalds be the same size (or at least, only as much as the smallest device 991da177e4SLinus Torvalds will be used). 1001da177e4SLinus Torvalds RAID-10 provides a variety of layouts that provide different levels 1011da177e4SLinus Torvalds of redundancy and performance. 1021da177e4SLinus Torvalds 1031da177e4SLinus Torvalds RAID-10 requires mdadm-1.7.0 or later, available at: 1041da177e4SLinus Torvalds 1051da177e4SLinus Torvalds ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/ 1061da177e4SLinus Torvalds 1071da177e4SLinus Torvalds If unsure, say Y. 1081da177e4SLinus Torvalds 10916a53eccSNeilBrownconfig MD_RAID456 11016a53eccSNeilBrown tristate "RAID-4/RAID-5/RAID-6 mode" 1111da177e4SLinus Torvalds depends on BLK_DEV_MD 1121da177e4SLinus Torvalds ---help--- 1131da177e4SLinus Torvalds A RAID-5 set of N drives with a capacity of C MB per drive provides 1141da177e4SLinus Torvalds the capacity of C * (N - 1) MB, and protects against a failure 1151da177e4SLinus Torvalds of a single drive. For a given sector (row) number, (N - 1) drives 1161da177e4SLinus Torvalds contain data sectors, and one drive contains the parity protection. 1171da177e4SLinus Torvalds For a RAID-4 set, the parity blocks are present on a single drive, 1181da177e4SLinus Torvalds while a RAID-5 set distributes the parity across the drives in one 1191da177e4SLinus Torvalds of the available parity distribution methods. 1201da177e4SLinus Torvalds 12116a53eccSNeilBrown A RAID-6 set of N drives with a capacity of C MB per drive 12216a53eccSNeilBrown provides the capacity of C * (N - 2) MB, and protects 12316a53eccSNeilBrown against a failure of any two drives. For a given sector 12416a53eccSNeilBrown (row) number, (N - 2) drives contain data sectors, and two 12516a53eccSNeilBrown drives contains two independent redundancy syndromes. Like 12616a53eccSNeilBrown RAID-5, RAID-6 distributes the syndromes across the drives 12716a53eccSNeilBrown in one of the available parity distribution methods. 12816a53eccSNeilBrown 1291da177e4SLinus Torvalds Information about Software RAID on Linux is contained in the 1301da177e4SLinus Torvalds Software-RAID mini-HOWTO, available from 1311da177e4SLinus Torvalds <http://www.tldp.org/docs.html#howto>. There you will also 1321da177e4SLinus Torvalds learn where to get the supporting user space utilities raidtools. 1331da177e4SLinus Torvalds 13416a53eccSNeilBrown If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To 1351da177e4SLinus Torvalds compile this code as a module, choose M here: the module 13616a53eccSNeilBrown will be called raid456. 1371da177e4SLinus Torvalds 1381da177e4SLinus Torvalds If unsure, say Y. 1391da177e4SLinus Torvalds 14029269553SNeilBrownconfig MD_RAID5_RESHAPE 14114f50b49SNeilBrown bool "Support adding drives to a raid-5 array" 14214f50b49SNeilBrown depends on MD_RAID456 14314f50b49SNeilBrown default y 14429269553SNeilBrown ---help--- 14529269553SNeilBrown A RAID-5 set can be expanded by adding extra drives. This 14629269553SNeilBrown requires "restriping" the array which means (almost) every 14729269553SNeilBrown block must be written to a different place. 14829269553SNeilBrown 14929269553SNeilBrown This option allows such restriping to be done while the array 15014f50b49SNeilBrown is online. 15129269553SNeilBrown 1524d2554d0SJustin Piszcz You will need mdadm version 2.4.1 or later to use this 1536f91fe88SNeilBrown feature safely. During the early stage of reshape there is 1546f91fe88SNeilBrown a critical section where live data is being over-written. A 1556f91fe88SNeilBrown crash during this time needs extra care for recovery. The 1566f91fe88SNeilBrown newer mdadm takes a copy of the data in the critical section 1576f91fe88SNeilBrown and will restore it, if necessary, after a crash. 15829269553SNeilBrown 15929269553SNeilBrown The mdadm usage is e.g. 16029269553SNeilBrown mdadm --grow /dev/md1 --raid-disks=6 16129269553SNeilBrown to grow '/dev/md1' to having 6 disks. 16229269553SNeilBrown 16329269553SNeilBrown Note: The array can only be expanded, not contracted. 16429269553SNeilBrown There should be enough spares already present to make the new 16529269553SNeilBrown array workable. 16629269553SNeilBrown 16714f50b49SNeilBrown If unsure, say Y. 16814f50b49SNeilBrown 1691da177e4SLinus Torvaldsconfig MD_MULTIPATH 1701da177e4SLinus Torvalds tristate "Multipath I/O support" 1711da177e4SLinus Torvalds depends on BLK_DEV_MD 1721da177e4SLinus Torvalds help 1731da177e4SLinus Torvalds Multipath-IO is the ability of certain devices to address the same 1741da177e4SLinus Torvalds physical disk over multiple 'IO paths'. The code ensures that such 1751da177e4SLinus Torvalds paths can be defined and handled at runtime, and ensures that a 1761da177e4SLinus Torvalds transparent failover to the backup path(s) happens if a IO errors 1771da177e4SLinus Torvalds arrives on the primary path. 1781da177e4SLinus Torvalds 1791da177e4SLinus Torvalds If unsure, say N. 1801da177e4SLinus Torvalds 1811da177e4SLinus Torvaldsconfig MD_FAULTY 1821da177e4SLinus Torvalds tristate "Faulty test module for MD" 1831da177e4SLinus Torvalds depends on BLK_DEV_MD 1841da177e4SLinus Torvalds help 1851da177e4SLinus Torvalds The "faulty" module allows for a block device that occasionally returns 1861da177e4SLinus Torvalds read or write errors. It is useful for testing. 1871da177e4SLinus Torvalds 1881da177e4SLinus Torvalds In unsure, say N. 1891da177e4SLinus Torvalds 1901da177e4SLinus Torvaldsconfig BLK_DEV_DM 1911da177e4SLinus Torvalds tristate "Device mapper support" 1921da177e4SLinus Torvalds depends on MD 1931da177e4SLinus Torvalds ---help--- 1941da177e4SLinus Torvalds Device-mapper is a low level volume manager. It works by allowing 1951da177e4SLinus Torvalds people to specify mappings for ranges of logical sectors. Various 1961da177e4SLinus Torvalds mapping types are available, in addition people may write their own 1971da177e4SLinus Torvalds modules containing custom mappings if they wish. 1981da177e4SLinus Torvalds 1991da177e4SLinus Torvalds Higher level volume managers such as LVM2 use this driver. 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds To compile this as a module, choose M here: the module will be 2021da177e4SLinus Torvalds called dm-mod. 2031da177e4SLinus Torvalds 2041da177e4SLinus Torvalds If unsure, say N. 2051da177e4SLinus Torvalds 206cc109201SBryn Reevesconfig DM_DEBUG 207cc109201SBryn Reeves boolean "Device mapper debugging support" 208cc109201SBryn Reeves depends on BLK_DEV_DM && EXPERIMENTAL 209cc109201SBryn Reeves ---help--- 210cc109201SBryn Reeves Enable this for messages that may help debug device-mapper problems. 211cc109201SBryn Reeves 212cc109201SBryn Reeves If unsure, say N. 213cc109201SBryn Reeves 2141da177e4SLinus Torvaldsconfig DM_CRYPT 2151da177e4SLinus Torvalds tristate "Crypt target support" 2161da177e4SLinus Torvalds depends on BLK_DEV_DM && EXPERIMENTAL 2171da177e4SLinus Torvalds select CRYPTO 2181da177e4SLinus Torvalds ---help--- 2191da177e4SLinus Torvalds This device-mapper target allows you to create a device that 2201da177e4SLinus Torvalds transparently encrypts the data on it. You'll need to activate 2211da177e4SLinus Torvalds the ciphers you're going to use in the cryptoapi configuration. 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds Information on how to use dm-crypt can be found on 2241da177e4SLinus Torvalds 2251da177e4SLinus Torvalds <http://www.saout.de/misc/dm-crypt/> 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds To compile this code as a module, choose M here: the module will 2281da177e4SLinus Torvalds be called dm-crypt. 2291da177e4SLinus Torvalds 2301da177e4SLinus Torvalds If unsure, say N. 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvaldsconfig DM_SNAPSHOT 2331da177e4SLinus Torvalds tristate "Snapshot target (EXPERIMENTAL)" 2341da177e4SLinus Torvalds depends on BLK_DEV_DM && EXPERIMENTAL 2351da177e4SLinus Torvalds ---help--- 2364d2554d0SJustin Piszcz Allow volume managers to take writable snapshots of a device. 2371da177e4SLinus Torvalds 2381da177e4SLinus Torvaldsconfig DM_MIRROR 2391da177e4SLinus Torvalds tristate "Mirror target (EXPERIMENTAL)" 2401da177e4SLinus Torvalds depends on BLK_DEV_DM && EXPERIMENTAL 2411da177e4SLinus Torvalds ---help--- 2421da177e4SLinus Torvalds Allow volume managers to mirror logical volumes, also 2431da177e4SLinus Torvalds needed for live data migration tools such as 'pvmove'. 2441da177e4SLinus Torvalds 2451da177e4SLinus Torvaldsconfig DM_ZERO 2461da177e4SLinus Torvalds tristate "Zero target (EXPERIMENTAL)" 2471da177e4SLinus Torvalds depends on BLK_DEV_DM && EXPERIMENTAL 2481da177e4SLinus Torvalds ---help--- 2491da177e4SLinus Torvalds A target that discards writes, and returns all zeroes for 2501da177e4SLinus Torvalds reads. Useful in some recovery situations. 2511da177e4SLinus Torvalds 2521da177e4SLinus Torvaldsconfig DM_MULTIPATH 2531da177e4SLinus Torvalds tristate "Multipath target (EXPERIMENTAL)" 2541da177e4SLinus Torvalds depends on BLK_DEV_DM && EXPERIMENTAL 2551da177e4SLinus Torvalds ---help--- 2561da177e4SLinus Torvalds Allow volume managers to support multipath hardware. 2571da177e4SLinus Torvalds 2581da177e4SLinus Torvaldsconfig DM_MULTIPATH_EMC 2591da177e4SLinus Torvalds tristate "EMC CX/AX multipath support (EXPERIMENTAL)" 2601da177e4SLinus Torvalds depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL 2611da177e4SLinus Torvalds ---help--- 2621da177e4SLinus Torvalds Multipath support for EMC CX/AX series hardware. 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvaldsendmenu 2651da177e4SLinus Torvalds 2669361401eSDavid Howellsendif 267