On Friday March 1, mooasun@yahoo.com wrote: > > Hello! > > Where could I get some information on "mdctl.conf"? > How to create and manage this file? > Is it used by mdctl? > Could it be a replacement for raidtab? > > Thanks, > Here is a copy of the man page for mdctl which has been updated a bit, and contains some information on how mdctl.conf is used. I hope to release mdctl-0.6 sometime next week which will include this man page and an improved mdctl. Hopefully this will answer your questions. NeilBrown .\" -*- nroff -*- .TH mdctl 8 .SH NAME mdctl \- a single program that can be used to control Linux md devices .SH SYNOPSIS .BI mdctl " [mode] <raiddevice> [options]" .SH DESCRIPTION RAID devices are virtual devices created from two or more real block devices. This allows multiple disks to be combined into a single filesystem, possibly with integrated redundancy to survive drive failure. Linux RAID devices are implemented through the md device driver. If you're using the .B /proc filesystem, .B /proc/mdstat gives you informations about md devices status. Currently, Linux supports .B LINEAR md devices, .B RAID0 (striping), .B RAID1 (mirrroring), .B RAID4 and .B RAID5. 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/people/mingo/raid-patches .br or .br http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ Recent kernels (2002) also support a mode known as .BR MULTIPATH . .B mdctl does not support MULTIPATH as yet. .B mdctl is a single program that can be used to control Linux md devices. It is intended to provide all the functionality (and more) of the mdtools and raidtools but with a very different interface. mdctl can perform all functions without a configuration file. There is the option of using a configuration file, but not in the same way that raidtools uses one. raidtools uses a configuration file to describe how to create a RAID array, and also uses this file partially to start a previously created RAID array. Further, raidtools requires the configuration file for such things as stopping a raid array which needs to know nothing about the array. The configuration file that can be used by mdctl lists two different things: .IP \(bu a list of devices that should be scanned for md sub-devices. .IP \(bu a list of md devices and information about how to identify each. The identity can consist of a UUID, and minor-number as recorded on the superblock, or a list of devices. .SH MODES mdctl has 7 major modes of operation: .TP .B Assemble This mode is used to assemble the parts of a previously created array into an active array. Components can be explicitly given or can be searched for. .B mdctl (optionally) checks that the components do form a bonafide array, and can, on request, fiddle superblock information so as to assemble a faulty array. .TP .B Build This is for building legacy arrays without superblocks. .TP .B Create This mode is used to create a new array with a superblock. It can progress in several step create-add-add-run or it can all happen with one command. .TP .B Detail 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. .TP .B Examine Examine a device to see if it is part of an md array, and print out the details of that array. .TP .B "Follow or Monitor" Monitor one or more md devices and act on any state changes. .TP .B Manage This is for odd bits an pieces like hotadd, hotremove, setfaulty, stop, readonly, readwrite. If an array is only partially setup by the Create or Assemble commands, subsequent Manage commands can finish the job. .SH OPTIONS Available options are: .TP .BR -A ", " --assemble Assemble an existing array .TP .BR -B ", " --build Build a legacy array without superblock .TP .BR -C ", " --create Create a new array .TP .BR -D ", " --detail Print detail of a given md array .TP .BR -E ", " --examine Print content of md superblock on device .TP .BR -F ", " --follow ", " --monitor Select .B Monitor mode. .TP .BR -h ", " --help This help message or, after above option, mode specific help message .TP .BR -V ", " --version Print version information for mdctl .TP .BR -v ", " --verbose Be more verbose about what is happening .SH For create or build: .TP .BR -c ", " --chunk= Specify chunk size of kibibytes. The default is 64. .TP .BR --rounding= rounding factor for linear array (==chunk size) .TP .BR -l ", " --level= 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. .TP .BR -p ", " --parity= Set raid5 parity algorithm. Options are: {left,right}-{,a}symmetric, la, ra, ls, rs. The default is left_symmetric. .TP .BR --layout= same as --parity .TP .BR -n ", " --raid-disks= number of active devices in array. .TP .BR -x ", " --spare-disks= number of spares (eXtras) to allow space for. .TP .BR -z ", " --size= Size (in K) of each drive in RAID1/4/5. If this is not specified (as it normally is not) the smallest drive (or partition) sets the size, though if there is a variance greater than 1%, a warning is issued. .SH For assemble: .TP .BR -u ", " --uuid= uuid of array to assemble. Devices which don't have this uuid are excluded .TP .BR -m ", " --super-minor= Minor number of device that array was created for. Devices which don't have this minor nmber are excluded. If you create an array as /dev/md1, then all superblock will contain the minor number 1, even if the array is late assembled as /dev/md2. .TP .BR -c ", " --config= config file. Default is .BR /etc/mdctl.conf . .TP .BR -s ", " --scan scan config file for missing information .TP .BR -f ", " --force Assemble the array even if some superblocks appear out-of-date .SH General management .TP .BR -a ", " --add add, or hotadd subsequent devices .TP .BR -r ", " --remove remove subsequent devices .TP .BR -f ", " --fail mark subsequent devices as faulty .TP .BR --set-faulty same as --fail .TP .BR -R ", " --run start a partially built array .TP .BR -S ", " --stop deactivate array, releasing all resources .TP .BR -o ", " --readonly mark array as readonly .TP .BR -w ", " --readwrite mark array as readwrite .SH CREATE MODE .HP 12 Usage: .B mdctl --create .I device .BI --chunk= X .BI --level= Y .br .BI --raid-disks= Z .I devices This usage will initialise a new md array and possibly associate some devices with it. If enough devices are given to complete the array, the array will be activated. Otherwise it will be left inactive to be completed and activated by subsequent management commands. As devices are added, they are checked to see if they contain 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 automatically be run, though the presence of a .B --run can override this caution. If the .B --size option is given, it is not necessary to list any subdevices in this command. They can be added later, before a .B --run. If no .B --size is given, the apparent size of the smallest drive given is used. The General Management options that are valid with --create are: .TP .B --run insist of running the array even if not all devices are present or some look odd. .TP .B --readonly start the array readonly - not supported yet. .SH ASSEMBLY MODE .HP 12 Usage: .B mdctl --assemble .I device options... .HP 12 Usage: .B mdctl --assemble --scan .I options... This usage assembles one or more raid arrays from pre-existing components. For each array, mdctl 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 .B --scan or is found from the config file. In the latter case, multiple md devices can be started with a single mdctl command. The identity can be given with the .B --uuid option, with the .B --super-minor option, can be found in in the config file, or will be taken from the super block on the first subdevice listed on the command line or in a subsequent .B --add command. Devices can be given on the .B --assemble command line, on subsequent .B 'mdctl --add' command lines, or from the config file. Only devices which have an md superblock which contains the right identity will be considered for any device. The config file is only used if explicitly named with .B --config or requested with .B --scan. In the later case, .B /etc/mdctl.conf is used. If .B --scan 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 .B --scan is not given and insufficent 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 .B --run flag. The config file is line oriented with, as usual, blank lines and lines beginning with a hash (or pound sign or sharp or number sign, whichever you like to call it) ignored. Lines that start with a blank are treated as continuations of the previous line. Each line contains a sequence of space-separated words, the first of which identified the type of line. Keywords are case-insensitive, and the first work on a line can be abbreviated to 3 letters. There are two types of lines. ARRAY and DEVICE. The DEVICE lines usually come first. All remaining words on the line are treated as names of devices, possibly containing wild cards (see glob(7)). These lists all the devices that mdctl is allowed to scan when looking for devices with RAID superblocks. Each line can contain multiple device names, and there can be multiple DEVICE lines. The ARRAY lines identiy actual array. The second word on the line should be the name of the device where the array is normally assembled, such as /dev/md1. Subsequent words identify the array. If multiple identities are given, then the array much match ALL identities to be considered a match. Each identity word has a tag, and equals sign, and some value. The options are: .TP .B uuid= The value should be a 128 bit uuid in hexadecimal, with punctuation interspersed if desired. This must match the uuid stored in the superblock. .TP .B super-minor= The value is an integer which indicates the minor number that was stored in the superblock when the array was created. When an array is created as /dev/mdX, then the minor number X is stored. .TP .B devices= The value is a comma separated list of device names. Precisely these devices will be used to assemble the array. Note that the devices listed there must also be listed on a DEVICE line. .SH BUILD MDOE .HP 12 Usage: .B mdctl --build .I device .BI --chunk= X .BI --level= Y .BI --raid-disks= Z .I devices This usage is similar to .B --create. 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 or linear. All devices must be listed and the array will be started once complete. '''.SH BUGS '''no known bugs. .SH TODO Finish and document Follow mode. .SH SEE ALSO .IR raidtab (5), .IR raid0run (8), .IR raidstop (8), .IR mkraid (8) - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
