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Document DM_DEFAULT_NAME_MANGLING_MODE environmental variable. (its default setting is build time configurable)
729 lines
19 KiB
Groff
729 lines
19 KiB
Groff
.TH DMSETUP 8 "Apr 06 2006" "Linux" "MAINTENANCE COMMANDS"
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.SH NAME
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dmsetup \- low level logical volume management
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.SH SYNOPSIS
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.ad l
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.B dmsetup clear
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.I device_name
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.br
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.B dmsetup create
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.I device_name
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.RB [ \-u
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.IR uuid ]
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.RB [ \-\-notable | \-\-table
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.RI < table >|
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.RS
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.IR table_file ]
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.RB [{ \-\-addnodeoncreate | \-\-addnodeonresume }]
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.RB [ \-\-readahead
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.RI [ \+ ]< sectors >| auto | none ]
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.RE
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.br
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.B dmsetup deps
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.RB [ \-o
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.IR options ]
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.RI [ device_name ]
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.br
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.B dmsetup help
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.RB [ \-c | \-C | \-\-columns ]
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.br
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.B dmsetup info
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.RI [ device_name ]
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.br
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.B dmsetup info
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.BR \-c | \-C | \-\-columns
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.RB [ \-\-noheadings ]
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.RB [ \-\-separator
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.IR separator ]
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.RS
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.RB [ \-o
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.IR fields ]
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.RB [ \-O | \-\-sort
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.IR sort_fields ]
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.RI [ device_name ]
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.RE
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.br
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.B dmsetup load
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.I device_name
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.RB [ \-\-table
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.RI < table >| table_file ]
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.br
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.B dmsetup ls
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.RB [ \-\-target
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.IR target_type ]
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.RB [ \-\-exec
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.IR command ]
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.RB [ \-\-tree ]
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.RS
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.RB [ \-o
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.IR options ]
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.RE
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.br
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.B dmsetup message
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.I device_name sector message
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.br
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.B dmsetup mknodes
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.RI [ device_name ]
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.br
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.B dmsetup mangle
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.RI [ device_name ]
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.br
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.B dmsetup reload
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.I device_name
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.RB [ \-\-table
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.RI < table >| table_file ]
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.br
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.B dmsetup wipe_table
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.I device_name
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.br
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.B dmsetup remove
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.RB [ \-f | \-\-force ]
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.RB [ \-\-retry ]
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.I device_name
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.br
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.B dmsetup remove_all
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.RB [ \-f | \-\-force ]
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.br
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.B dmsetup rename
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.I device_name new_name
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.br
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.B dmsetup rename
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.I device_name
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.B \-\-setuuid
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.I uuid
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.br
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.B dmsetup resume
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.I device_name
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.RB [{ \-\-addnodeoncreate | \-\-addnodeonresume }]
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.RS
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.RB [ \-\-readahead
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.RI [ \+ ]< sectors >| auto | none ]
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.RE
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.br
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.B dmsetup setgeometry
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.I device_name cyl head sect start
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.br
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.B dmsetup splitname
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.I device_name
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.RI [ subsystem ]
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.br
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.B dmsetup status
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.RB [ \-\-target
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.IR target_type ]
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.RB [ \-\-noflush ]
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.RI [ device_name ]
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.br
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.B dmsetup suspend
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.RB [ \-\-nolockfs ]
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.RB [ \-\-noflush ]
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.I device_name
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.br
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.B dmsetup table
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.RB [ \-\-target
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.IR target_type ]
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.RB [ \-\-showkeys ]
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.RI [ device_name ]
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.br
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.B dmsetup targets
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.br
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.B dmsetup udevcomplete
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.I cookie
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.br
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.B dmsetup udevcomplete_all
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.RI [ age_in_minutes ]
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.br
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.B dmsetup udevcookies
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.br
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.B dmsetup udevcreatecookie
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.br
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.B dmsetup udevflags
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.I cookie
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.br
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.B dmsetup udevreleasecookie
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.RI [ cookie ]
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.br
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.B dmsetup version
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.br
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.B dmsetup wait
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.RB [ \-\-noflush ]
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.I device_name
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.RI [ event_nr ]
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.br
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.B devmap_name
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.I major minor
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.br
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.B devmap_name
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.I major:minor
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.ad b
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.SH DESCRIPTION
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dmsetup manages logical devices that use the device-mapper driver.
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Devices are created by loading a table that specifies a target for
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each sector (512 bytes) in the logical device.
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The first argument to dmsetup is a command.
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The second argument is the logical device name or uuid.
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Invoking the command as \fBdevmap_name\fP is equivalent to
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.br
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\fBdmsetup info \-c \-\-noheadings \-j \fImajor\fB \-m \fIminor\fP.
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.SH OPTIONS
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.TP
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.B \-\-addnodeoncreate
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Ensure /dev/mapper node exists after dmsetup create.
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.TP
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.B \-\-addnodeonresume
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Ensure /dev/mapper node exists after dmsetup resume (default with udev).
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.TP
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.B \-\-checks
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Perform additional checks on the operations requested and report
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potential problems. Useful when debugging scripts.
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In some cases these checks may slow down operations noticeably.
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.TP
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.BR \-c | \-C | \-\-columns
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Display output in columns rather than as Field: Value lines.
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.TP
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.BR \-h | \-\-help
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Outputs a summary of the commands available, optionally including
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the list of report fields (synonym with \fBhelp\fP command).
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.TP
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.B \-\-inactive
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When returning any table information from the kernel report on the
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inactive table instead of the live table.
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Requires kernel driver version 4.16.0 or above.
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.TP
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.IR \fB\-\-manglename \ < mangling_mode >
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Mangle any character not on a whitelist using mangling_mode when
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processing device-mapper device names and UUIDs. The names and UUIDs
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are mangled on input and unmangled on output where the mangling_mode
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is one of: none (no mangling), hex (always do the mangling) and auto
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(only do the mangling if not mangled yet, do nothing if already
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mangled, error on mixed; this is used by default).
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Character whitelist: 0-9, A-Z, a-z, #+-.:=@_. This whitelist is
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also supported by udev. Any character not on a whitelist is replaced
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with its hex value (two digits) prefixed by \\x.
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Mangling mode could be also set through
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.B DM_DEFAULT_NAME_MANGLING_MODE
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environment variable.
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.TP
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.BR \-j | \-\-major\ \fImajor
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Specify the major number.
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.TP
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.BR \-m | \-\-minor\ \fIminor
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Specify the minor number.
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.TP
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.BR \-n | \-\-noheadings
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Suppress the headings line when using columnar output.
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.TP
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.B \-\-noopencount
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Tell the kernel not to supply the open reference count for the device.
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.TP
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.B \-\-notable
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When creating a device, don't load any table.
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.TP
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.B \-\-noudevrules
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Do not allow udev to manage nodes for devices in device-mapper directory.
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.TP
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.B \-\-noudevsync
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Do not synchronise with udev when creating, renaming or removing devices.
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.TP
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.BR \-o | \-\-options
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Specify which fields to display.
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.TP
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.IR \fB\-\-readahead \ [ \+ ]< sectors >| auto | none
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Specify read ahead size in units of sectors.
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The default value is \fIauto\fP which allows the kernel to choose
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a suitable value automatically. The \fI\+\fP prefix lets you
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specify a minimum value which will not be used if it is
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smaller than the value chosen by the kernel.
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The value \fInone\fP is equivalent to specifying zero.
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.TP
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.BR \-r | \-\-readonly
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Set the table being loaded read-only.
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.TP
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.IR \fB\-\-table \ < table >
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Specify a one-line table directly on the command line.
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.TP
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.B \-\-udevcookie \fIcookie
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Use cookie for udev synchronisation.
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Note: Same cookie should be used for same type of operations i.e. creation of
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multiple different devices. It's not adviced to combine different
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operations on the single device.
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.TP
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.BR \-u | \-\-uuid
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Specify the uuid.
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.TP
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.BR \-y | \-\-yes
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Answer yes to all prompts automatically.
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.TP
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.BR \-v | \-\-verbose \ [ \-v | \-\-verbose ]
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Produce additional output.
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.TP
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.B \-\-verifyudev
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If udev synchronisation is enabled, verify that udev operations get performed
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correctly and try to fix up the device nodes afterwards if not.
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.TP
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.B \-\-version
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Display the library and kernel driver version.
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.br
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.SH COMMANDS
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.TP
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.B clear
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.I device_name
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.br
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Destroys the table in the inactive table slot for device_name.
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.br
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.TP
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.B create
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.I device_name
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.RB [ \-u
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.IR uuid ]
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.RB [ \-\-notable | \-\-table
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.RI < \fItable >| table_file ]
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.RB [{ \-\-addnodeoncreate | \-\-addnodeonresume }]
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.RB [ \-\-readahead
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.RI [ + ]< sectors >| auto | none ]
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.br
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Creates a device with the given name.
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If table_file or <table> is supplied, the table is loaded and made live.
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Otherwise a table is read from standard input unless \fB\-\-notable\fP is used.
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The optional uuid can be used in place of
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device_name in subsequent dmsetup commands.
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If successful a device will appear as
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/dev/mapper/<device-name>.
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See below for information on the table format.
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.br
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.TP
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.B deps
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.RB [ \-o
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.IR options ]
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.RI [ device_name ]
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.br
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Outputs a list of devices referenced by the live table for the specified
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device. Device names on output can be customised by following options:
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devno (major and minor pair, used by default), blkdevname (block device name),
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devname (map name for device-mapper devices, equal to blkdevname otherwise).
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.br
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.TP
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.B help
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.RB [ \-c | \-C | \-\-columns ]
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.br
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Outputs a summary of the commands available, optionally including
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the list of report fields.
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.br
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.TP
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.B info
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.RI [ device_name ]
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.br
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Outputs some brief information about the device in the form:
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.RS
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.RS
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State: SUSPENDED|ACTIVE, READ-ONLY
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Tables present: LIVE and/or INACTIVE
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Open reference count
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Last event sequence number (used by \fBwait\fP)
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Major and minor device number
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Number of targets in the live table
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UUID
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.RE
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.RE
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.br
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.TP
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.B info
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.BR \-c | \-C | \-\-columns
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.RB [ \-\-noheadings ]
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.RB [ \-\-separator
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.IR separator ]
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.RB [ \-o
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.IR fields ]
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.RB [ \-O | \-\-sort
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.IR sort_fields ]
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.RI [ device_name ]
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.br
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Output you can customise.
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Fields are comma-separated and chosen from the following list:
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name, major, minor, attr, open, segments, events, uuid.
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Attributes are: (L)ive, (I)nactive, (s)uspended, (r)ead-only, read-(w)rite.
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Precede the list with '+' to append
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to the default selection of columns instead of replacing it.
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Precede any sort_field with - for a reverse sort on that column.
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.br
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.TP
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.B ls
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.RB [ \-\-target
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.IR target_type ]
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.RB [ \-\-exec
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.IR command ]
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.RB [ \-\-tree ]
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.RB [ \-o
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.IR options ]
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.br
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List device names. Optionally only list devices that have at least
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one target of the specified type. Optionally execute a command for
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each device. The device name is appended to the supplied command.
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Device names on output can be customised by following options: devno (major
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and minor pair, used by default), blkdevname (block device name),
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devname (map name for device-mapper devices, equal to blkdevname otherwise).
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\fB\-\-tree\fP displays dependencies between devices as a tree.
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It accepts a comma-separate list of options.
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Some specify the information displayed against each node:
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device/nodevice; blkdevname; active, open, rw, uuid.
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Others specify how the tree is displayed:
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ascii, utf, vt100; compact, inverted, notrunc.
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.br
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.HP
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.BR load | reload
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.I device_name
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.RB [ \-\-table
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.RI < table >| table_file ]
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.br
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Loads <table> or table_file into the inactive table slot for device_name.
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If neither is supplied, reads a table from standard input.
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.br
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.HP
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.B wipe_table
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.I device_name
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.br
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Wait for any I/O in-flight through the device to complete, then
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replace the table with a new table that fails any new I/O
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sent to the device. If successful, this should release any devices
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held open by the device's table(s).
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.br
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.HP
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.B message
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.I device_name sector message
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.br
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Send message to target. If sector not needed use 0.
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.br
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.HP
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.B mknodes
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.RI [ device_name ]
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.br
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Ensure that the node in /dev/mapper for device_name is correct.
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If no device_name is supplied, ensure that all nodes in /dev/mapper
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correspond to mapped devices currently loaded by the device-mapper kernel
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driver, adding, changing or removing nodes as necessary.
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.br
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.HP
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.B mangle
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.RI [ device_name ]
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.br
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Ensure existing device-mapper device name and UUID is in the correct mangled
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form containing only whitelisted characters (supported by udev) and do
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a rename if necessary. Any character not on the whitelist will be mangled
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based on the \fB\-\-manglename\fP setting. Automatic rename works only for device
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names and not for device UUIDs because the kernel does not allow changing
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the UUID of active devices. Any incorrect UUIDs are reported only and they
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must be manually corrected by deactivating the device first and then
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reactivating it with proper mangling mode used (see also \fB\-\-manglename\fP).
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.br
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.HP
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.B remove
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.RB [ \-f | \-\-force ]
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.RB [ \-\-retry ]
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.I device_name
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.br
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Removes a device. It will no longer be visible to dmsetup.
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Open devices cannot be removed except with older kernels
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that contain a version of device-mapper prior to 4.8.0.
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In this case the device will be deleted when its open_count
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drops to zero. From version 4.8.0 onwards, if a device can't
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be removed because an uninterruptible process is waiting for
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I/O to return from it, adding \fB\-\-force\fP will replace the table
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with one that fails all I/O, which might allow the
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process to be killed. If an attempt to remove a device fails,
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perhaps because a process run from a quick udev rule
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temporarily opened the device, the \fB\-\-retry\fP option will cause
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the operation to be retried for a few seconds before failing.
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Do NOT combine \fB\-\-force\fP and \fB\-\-udevcookie\fP,
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as udev may start to process udev rules in the middle of error target
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replacement and result in nondeterministic result.
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.br
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.HP
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.B remove_all
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.RB [ \-f | \-\-force ]
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.br
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Attempts to remove all device definitions i.e. reset the driver.
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Use with care! From version 4.8.0 onwards, if devices can't
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be removed because uninterruptible processes are waiting for
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I/O to return from them, adding \fB\-\-force\fP will replace the table
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with one that fails all I/O, which might allow the
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process to be killed. This also runs \fBmknodes\fP afterwards.
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.br
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.HP
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.B rename
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.I device_name new_name
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.br
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Renames a device.
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.br
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.HP
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.B rename
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.I device_name
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.B \-\-setuuid
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.I uuid
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.br
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Sets the uuid of a device that was created without a uuid.
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After a uuid has been set it cannot be changed.
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.br
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.TP
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.B resume
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.I device_name
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.RB [{ \-\-addnodeoncreate | \-\-addnodeonresume }]
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.RB [ \-\-readahead
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.RI [ + ]< sectors >| auto | none ]
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.br
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Un-suspends a device.
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If an inactive table has been loaded, it becomes live.
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Postponed I/O then gets re-queued for processing.
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.br
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.TP
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.B setgeometry \fIdevice_name cyl head sect start
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.br
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Sets the device geometry to C/H/S.
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.br
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.HP
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.B splitname
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.I device_name
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.RI [ subsystem ]
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.br
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Splits given device name into subsystem constituents.
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Default subsystem is LVM.
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.br
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.TP
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.B status
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.RB [ \-\-target
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.IR target_type ]
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.RB [ \-\-noflush ]
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.RI [ device_name ]
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.br
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Outputs status information for each of the device's targets.
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With \fB\-\-target\fP, only information relating to the specified target type
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any is displayed. With \fB\-\-noflush\fP, the thin target (from version 1.3.0)
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doesn't commit any outstanding changes to disk before reporting its statistics.
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.br
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.HP
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.B suspend
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.RB [ \-\-nolockfs ]
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.RB [ \-\-noflush ]
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.I device_name
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.br
|
|
Suspends a device. Any I/O that has already been mapped by the device
|
|
but has not yet completed will be flushed. Any further I/O to that
|
|
device will be postponed for as long as the device is suspended.
|
|
If there's a filesystem on the device which supports the operation,
|
|
an attempt will be made to sync it first unless \fB\-\-nolockfs\fP is specified.
|
|
Some targets such as recent (October 2006) versions of multipath may support
|
|
the \fB\-\-noflush\fP option. This lets outstanding I/O that has not yet reached the
|
|
device to remain unflushed.
|
|
.br
|
|
.TP
|
|
.B table
|
|
.RB [ \-\-target
|
|
.IR target_type ]
|
|
.RB [ \-\-showkeys ]
|
|
.RI [ device_name ]
|
|
.br
|
|
Outputs the current table for the device in a format that can be fed
|
|
back in using the create or load commands.
|
|
With \fB\-\-target\fP, only information relating to the specified target type
|
|
is displayed.
|
|
Encryption keys are suppressed in the table output for the crypt
|
|
target unless the \fB\-\-showkeys\fP parameter is supplied.
|
|
.br
|
|
.TP
|
|
.B targets
|
|
.br
|
|
Displays the names and versions of the currently-loaded targets.
|
|
.br
|
|
.HP
|
|
.B udevcomplete
|
|
.I cookie
|
|
.br
|
|
Wake any processes that are waiting for udev to complete processing the specified cookie.
|
|
.br
|
|
.HP
|
|
.B udevcomplete_all
|
|
.RI [ age_in_minutes ]
|
|
.br
|
|
Remove all cookies older than the specified number of minutes.
|
|
Any process waiting on a cookie will be resumed immediately.
|
|
.br
|
|
.HP
|
|
.B udevcookies
|
|
.br
|
|
List all existing cookies. Cookies are system-wide semaphores with keys
|
|
prefixed by two predefined bytes (0x0D4D).
|
|
.br
|
|
.TP
|
|
.B udevcreatecookie
|
|
.br
|
|
Creates a new cookie to synchronize actions with udev processing.
|
|
The output is a cookie value. Normally we don't need to create cookies since
|
|
dmsetup creates and destroys them for each action automatically. However, we can
|
|
generate one explicitly to group several actions together and use only one
|
|
cookie instead. We can define a cookie to use for each relevant command by using
|
|
\fB\-\-udevcookie\fP option. Alternatively, we can export this value into the environment
|
|
of the dmsetup process as \fBDM_UDEV_COOKIE\fP variable and it will be used automatically
|
|
with all subsequent commands until it is unset.
|
|
Invoking this command will create system-wide semaphore that needs to be cleaned
|
|
up explicitly by calling udevreleasecookie command.
|
|
.br
|
|
.HP
|
|
.B udevflags
|
|
.I cookie
|
|
.br
|
|
Parses given cookie value and extracts any udev control flags encoded.
|
|
The output is in environment key format that is suitable for use in udev
|
|
rules. If the flag has its symbolic name assigned then the output is
|
|
DM_UDEV_FLAG_<flag_name>='1', DM_UDEV_FLAG<flag_position>='1' otherwise.
|
|
Subsystem udev flags don't have symbolic names assigned and these ones are
|
|
always reported as DM_SUBSYSTEM_UDEV_FLAG<flag_position>='1'. There are
|
|
16 udev flags altogether.
|
|
.br
|
|
.HP
|
|
.B udevreleasecookie
|
|
.RI [ cookie ]
|
|
.br
|
|
Waits for all pending udev processing bound to given cookie value and clean up
|
|
the cookie with underlying semaphore. If the cookie is not given directly,
|
|
the command will try to use a value defined by \fBDM_UDEV_COOKIE\fP environment variable.
|
|
.br
|
|
.TP
|
|
.B version
|
|
.br
|
|
Outputs version information.
|
|
|
|
.TP
|
|
.B wait
|
|
.RB [ \-\-noflush ]
|
|
.I device_name
|
|
.RI [ event_nr ]
|
|
.br
|
|
Sleeps until the event counter for device_name exceeds event_nr.
|
|
Use \fB\-v\fP to see the event number returned.
|
|
To wait until the next event is triggered, use \fBinfo\fP to find
|
|
the last event number.
|
|
With \fB\-\-noflush\fP, the thin target (from version 1.3.0) doesn't commit
|
|
any outstanding changes to disk before reporting its statistics.
|
|
.SH TABLE FORMAT
|
|
Each line of the table specifies a single target and is of the form:
|
|
.P
|
|
.I logical_start_sector num_sectors
|
|
.B target_type
|
|
.RI < target_args >
|
|
.P
|
|
Simple target types and <target_args> include:
|
|
.HP
|
|
.B linear
|
|
.I destination_device start_sector
|
|
.br
|
|
The traditional linear mapping.
|
|
.HP
|
|
.B striped
|
|
.I num_stripes chunk_size
|
|
.RI [ destination
|
|
.IR start_sector ]+
|
|
.br
|
|
Creates a striped area.
|
|
.br
|
|
e.g. striped 2 32 /dev/hda1 0 /dev/hdb1 0
|
|
will map the first chunk (16k) as follows:
|
|
.RS
|
|
.RS
|
|
LV chunk 1 -> hda1, chunk 1
|
|
LV chunk 2 -> hdb1, chunk 1
|
|
LV chunk 3 -> hda1, chunk 2
|
|
LV chunk 4 -> hdb1, chunk 2
|
|
etc.
|
|
.RE
|
|
.RE
|
|
.TP
|
|
.B error
|
|
.br
|
|
Errors any I/O that goes to this area. Useful for testing or
|
|
for creating devices with holes in them.
|
|
.TP
|
|
.B zero
|
|
.br
|
|
Returns blocks of zeroes on reads. Any data written is discarded silently.
|
|
This is a block-device equivalent of the /dev/zero character-device data sink
|
|
described in \fBnull\fP(4).
|
|
.P
|
|
More complex targets include:
|
|
.TP
|
|
.B crypt
|
|
.br
|
|
Transparent encryption of block devices using the kernel crypto API.
|
|
.TP
|
|
.B delay
|
|
.br
|
|
Delays reads and/or writes to different devices. Useful for testing.
|
|
.TP
|
|
.B flakey
|
|
.br
|
|
Creates a similar mapping to the linear target but
|
|
exhibits unreliable behaviour periodically.
|
|
Useful for simulating failing devices when testing.
|
|
.TP
|
|
.B mirror
|
|
.br
|
|
Mirrors data across two or more devices.
|
|
.HP
|
|
.B multipath
|
|
.br
|
|
Mediates access through multiple paths to the same device.
|
|
.TP
|
|
.BR raid
|
|
.br
|
|
Offers an interface to the kernel's software raid driver, md.
|
|
.HP
|
|
.B snapshot
|
|
.br
|
|
Supports snapshots of devices.
|
|
.P
|
|
To find out more about the various targets and their table formats and status
|
|
lines, please read the files in the Documentation/device-mapper directory in
|
|
the kernel source tree.
|
|
(Your distribution might include a copy of this information in the
|
|
documentation directory for the device-mapper package.)
|
|
|
|
.SH EXAMPLES
|
|
|
|
# A table to join two disks together
|
|
.br
|
|
.br
|
|
0 1028160 linear /dev/hda 0
|
|
.br
|
|
1028160 3903762 linear /dev/hdb 0
|
|
|
|
|
|
# A table to stripe across the two disks,
|
|
.br
|
|
# and add the spare space from
|
|
.br
|
|
# hdb to the back of the volume
|
|
|
|
0 2056320 striped 2 32 /dev/hda 0 /dev/hdb 0
|
|
.br
|
|
2056320 2875602 linear /dev/hdb 1028160
|
|
|
|
.SH ENVIRONMENT VARIABLES
|
|
.TP
|
|
.B DM_DEV_DIR
|
|
The device directory name.
|
|
Defaults to "/dev" and must be an absolute path.
|
|
.TP
|
|
.B DM_UDEV_COOKIE
|
|
A cookie to use for all relevant commands to synchronize with udev processing.
|
|
It is an alternative to using \fB\-\-udevcookie\fP option.
|
|
.TP
|
|
.B DM_DEFAULT_NAME_MANGLING_MODE
|
|
A default mangling mode. Defaults to "#DEFAULT_MANGLING#"
|
|
and it is an alternative to using \fB\-\-manglename\fP option.
|
|
|
|
.SH AUTHORS
|
|
Original version: Joe Thornber (thornber@redhat.com)
|
|
|
|
.SH SEE ALSO
|
|
Device-mapper resource page: http://sources.redhat.com/dm/
|