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diff --git a/mdadm.man b/mdadm.man new file mode 100644 index 0000000..6c7895d --- /dev/null +++ b/mdadm.man @@ -0,0 +1,423 @@ +mdadm(8) mdadm(8) + + + +NNAAMMEE + mdadm - manage MD devices _a_k_a Linux Software Raid. + + +SSYYNNOOPPSSIISS + mmddaaddmm _[_m_o_d_e_] _<_r_a_i_d_d_e_v_i_c_e_> _[_o_p_t_i_o_n_s_] _<_s_u_b_d_e_v_i_c_e_s_> + + +DDEESSCCRRIIPPTTIIOONN + RAID devices are virtual devices created from two or more + real block devices. This allows multiple devices (typi- + cally disk drives or partitions there-of) to be combined + into a single device to hold (for example) a single + filesystem. Some RAID levels included redundancy and so + can survive some degree of device failure. + + Linux Software RAID devices are implemented through the md + (Multiple Devices) device driver. + + Currently, Linux supports LLIINNEEAARR md devices, RRAAIIDD00 (strip- + ing), RRAAIIDD11 (mirroring), RRAAIIDD44 and RRAAIIDD55.. + + Recent kernels (2002) also support a mode known as MMUULLTTII-- + PPAATTHH. mmddaaddmm does not support MULTIPATH as yet. + + mmddaaddmm is a program that can be used to create, manage, and + monitor MD devices. As such it provides a similar set of + functionality to the rraaiiddttoooollss packages. The key differ- + ences between mmddaaddmm and rraaiiddttoooollss are: + + +o mmddaaddmm is a single program and not a collection of pro- + grams. + + +o mmddaaddmm can perform (almost) all of its functions with- + out having a configuration file. Also mdadm helps + with management of the configuration file. + + +o mmddaaddmm can provide information about your arrays + (through Detail and Examine) that rraaiiddttoooollss cannot. + + +o rraaiiddttoooollss can manage MULTIPATH devices which mmddaaddmm + cannot yet manage. + + +MMOODDEESS + mdadm has 7 major modes of operation: + + AAsssseemmbbllee + Assemble the parts of a previously created array + into an active array. Components can be explicitly + given or can be searched for. mmddaaddmm checks that + the components do form a bona fide array, and can, + on request, fiddle superblock information so as to + assemble a faulty array. + + + BBuuiilldd Build a legacy array without per-device + superblocks. + + + CCrreeaattee Create a new array with per-device superblocks. + + + DDeettaaiill Display the details of a given md device. Details + include the RAID level, the number of devices, + which ones are faulty (if any), and the array UUID. + + + EExxaammiinnee + Examine a device to see if it is part of an md + array, and print out the details of that array. + This mode can also be used to examine a large num- + ber of devices and to print out a summary of the + arrays found in a format suitable for the + mmddaaddmm..ccoonnff configuration file. + + + FFoollllooww oorr MMoonniittoorr + Monitor one or more md devices and act on any state + changes. + + + MMaannaaggee This is for odd bits an pieces like hotadd, + hotremove, setfaulty, stop, readonly, readwrite. + + +OOPPTTIIOONNSS + Available options are: + + + --AA, ----aasssseemmbbllee + Assemble an existing array. + + + --BB, ----bbuuiilldd + Build a legacy array without superblocks. + + + --CC, ----ccrreeaattee + Create a new array. + + + --DD, ----ddeettaaiill + Print detail of one or more md devices. + + + --EE, ----eexxaammiinnee + Print content of md superblock on device(s). + + + --FF, ----ffoollllooww, ----mmoonniittoorr + Select MMoonniittoorr mode. + + + --hh, ----hheellpp + Display help message or, after above option, mode + specific help message. + + + --VV, ----vveerrssiioonn + Print version information for mdadm. + + + --vv, ----vveerrbboossee + Be more verbose about what is happening. + + + --bb, ----bbrriieeff + Be less verbose. This is used with ----ddeettaaiill and + ----eexxaammiinnee. + + +FFoorr ccrreeaattee oorr bbuuiilldd:: + --cc, ----cchhuunnkk== + Specify chunk size of kibibytes. The default is + 64. + + + ----rroouunnddiinngg== + Specify rounding factor for linear array (==chunk + size) + + + --ll, ----lleevveell== + Set raid level. Options are: linear, raid0, 0, + stripe, raid1, 1, mirror, raid5, 4, raid5, 5. + Obviously some of these are synonymous. Only the + first 4 are valid when Building. + + + --pp, ----ppaarriittyy== + Set raid5 parity algorithm. Options are: + {left,right}-{,a}symmetric, la, ra, ls, rs. The + default is left-symmetric. + + + ----llaayyoouutt== + same as --parity + + + --nn, ----rraaiidd--ddiisskkss== + number of active devices in array. + + + --xx, ----ssppaarree--ddiisskkss== + number of spare (eXtra) disks in initial array. + Spares can be added and removed later. + + + --zz, ----ssiizzee== + Amount (in Kibibytes) of space to use from each + drive in RAID1/4/5. This must be a multiple of the + chunk size, and must leave about 128Kb of space at + the end of the drive for the RAID superblock. If + this is not specified (as it normally is not) the + smallest drive (or partition) sets the size, though + if there is a variance among the drives of greater + than 1%, a warning is issued. + + +FFoorr aasssseemmbbllee:: + --uu, ----uuuuiidd== + uuid of array to assemble. Devices which don't have + this uuid are excluded + + + --mm, ----ssuuppeerr--mmiinnoorr== + Minor number of device that array was created for. + Devices which don't have this minor number are + excluded. If you create an array as /dev/md1, then + all superblock will contain the minor number 1, + even if the array is later assembled as /dev/md2. + + + --cc, ----ccoonnffiigg== + config file. Default is //eettcc//mmddaaddmm..ccoonnff. + + + --ss, ----ssccaann + scan config file for missing information + + + --ff, ----ffoorrccee + Assemble the array even if some superblocks appear + out-of-date + + + --RR, ----rruunn + Attempt to start the array even if fewer drives + were given than are needed for a full array. Nor- + mally if not all drives are found and ----ssccaann is not + used, then the array will be assembled but not + started. With ----rruunn an attempt will be made to + start it anyway. + + +GGeenneerraall mmaannaaggeemmeenntt + --aa, ----aadddd + hotadd listed devices. + + + --rr, ----rreemmoovvee + remove listed devices. The must not be active. + i.e. they should be failed or spare devices. + + + --ff, ----ffaaiill + mark listed devices as faulty. + + + ----sseett--ffaauullttyy + same as --fail. + + + --RR, ----rruunn + start a partially built array. + + + --SS, ----ssttoopp + deactivate array, releasing all resources. + + + --oo, ----rreeaaddoonnllyy + mark array as readonly. + + + --ww, ----rreeaaddwwrriittee + mark array as readwrite. + + + +AASSSSEEMMBBLLYY MMOODDEE + Usage: mmddaaddmm ----aasssseemmbbllee _d_e_v_i_c_e _o_p_t_i_o_n_s_._._. + + Usage: mmddaaddmm ----aasssseemmbbllee ----ssccaann _o_p_t_i_o_n_s_._._. + + + This usage assembles one or more raid arrays from pre- + existing components. For each array, mdadm needs to know + the md device, the identity of the array, and a number of + sub devices. These can be found in a number of ways. + + The md device is either given before ----ssccaann or is found + from the config file. In the latter case, multiple md + devices can be started with a single mdadm command. + + The identity can be given with the ----uuuuiidd option, with the + ----ssuuppeerr--mmiinnoorr option, can be found in in the config file, + or will be taken from the super block on the first subde- + vice listed on the command line. + + Devices can be given on the ----aasssseemmbbllee command line or + from the config file. Only devices which have an md + superblock which contains the right identity will be con- + sidered for any device. + + The config file is only used if explicitly named with + ----ccoonnffiigg or requested with ----ssccaann.. In the later case, + //eettcc//mmddaaddmm..ccoonnff is used. + + If ----ssccaann is not given, then the config file will only be + used to find the identity of md arrays. + + Normally the array will be started after it is assembled. + However is ----ssccaann is not given and insufficient drives + were lists to start a complete (non-degraded) array, then + the array is not started (to guard against usage errors). + To insist that the array be started in this case (as may + work for RAID1 or RAID5), give the ----rruunn flag. + + + +BBUUIILLDD MMOODDEE + Usage: mmddaaddmm ----bbuuiilldd _d_e_v_i_c_e ----cchhuunnkk==_X ----lleevveell==_Y ----rraaiidd-- + ddiisskkss==_Z _d_e_v_i_c_e_s + + + This usage is similar to ----ccrreeaattee. The difference is that + it creates a legacy array without a superblock. With these + arrays there is no difference between initially creating + the array and subsequently assembling the array, except + that hopefully there is useful data there in the second + case. + + The level may only be 0, raid0, or linear. All devices + must be listed and the array will be started once com- + plete. + + +CCRREEAATTEE MMOODDEE + Usage: mmddaaddmm ----ccrreeaattee _d_e_v_i_c_e ----cchhuunnkk==_X ----lleevveell==_Y + ----rraaiidd--ddiisskkss==_Z _d_e_v_i_c_e_s + + + This usage will initialise a new md array, associate some + devices with it, and activate the array. + + As devices are added, they are checked to see if they con- + tain raid superblocks or filesystems. They are also check + to see if the variance in device size exceeds 1%. + + If any discrepancy is found, the array will not automati- + cally be run, though the presence of a ----rruunn can override + this caution. + + + The General Management options that are valid with --cre- + ate are: + + ----rruunn insist of running the array even if some devices + look like they might be in use. + + + ----rreeaaddoonnllyy + start the array readonly - not supported yet. + + +DDEETTAAIILL MMOODDEE + Usage: mmddaaddmm ----ddeettaaiill [----bbrriieeff] _d_e_v_i_c_e _._._. + + + This usage sill print out the details of the given array + including a list of component devices. To determine names + for the devices, mmddaaddmm searches //ddeevv for device files with + the right major and minor numbers. + + With ----bbrriieeff mmddaaddmm prints a single line that identifies + the level, number of disks, and UUID of the array. This + line is suitable for inclusion in //eettcc//mmddaaddmm..ccoonnff. + + +EEXXAAMMIINNEE MMOODDEE + Usage: mmddaaddmm ----eexxaammiinnee [----ssccaann] [----bbrriieeff] _d_e_v_i_c_e _._._. + + This usage will examine some block devices to see if that + have a valid RAID superblock on them. The information in + each valid raid superblock will be printed. + + If ----ssccaann is used, the no devices should be listed, and + the complete set of devices identified in the configura- + tion file are checked. ----ssccaann implies ----bbrriieeff but this + implication can be countered by specifying ----vveerrbboossee. + + With ----bbrriieeff mmddaaddmm will output an config file entry of + each distinct array that was found. This entry will list + the UUID, the raid level, and a list of the individual + devices on which a superblock for that array was found. + This output will by syntactically suitable for inclusion + in the configuration file, but should NNOOTT be used blindly. + Often the array description that you want in the configu- + ration file is much less specific than that given by mmddaaddmm + --BBss. For example, you normally do not want to list the + devices, particularly if they are SCSI devices. + + + +FFIILLEESS + //pprroocc//mmddssttaatt + If you're using the //pprroocc filesystem, //pprroocc//mmddssttaatt gives + you informations about md devices status. This file is + not currently used by mmddaaddmm. + + + //eettcc//mmddaaddmm..ccoonnff + The config file lists which devices may be scanned to see + if they contain MD super block, and gives identifying + information (e.g. UUID) about known MD arrays. See + mmddaaddmm..ccoonnff(5) for more details. + + + +TTOODDOO + Finish and document Follow mode. + + +SSEEEE AALLSSOO + For information on the various levels of RAID, check out: + + + http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/ + + for new releases of the RAID driver check out: + + + ftp://ftp.kernel.org/pub/linux/kernel/peo- + ple/mingo/raid-patches + + or + + http://www.cse.unsw.edu.au/~neilb/patches/linux- + stable/ + + mmddaaddmm..ccoonnff(5), mmdd(4). + + _r_a_i_d_t_a_b(5), _r_a_i_d_0_r_u_n(8), _r_a_i_d_s_t_o_p(8), _m_k_r_a_i_d(8) + + + + mdadm(8) |