dmsetup(8) -- Linux man page
NAMEdmsetup - low level logical volume management
SYNOPSISdmsetup create device_name [-u uuid] [--notable] [table_file]
dmsetup remove device_name
dmsetup suspend device_name
dmsetup resume device_name
dmsetup load device_name [table_file]
dmsetup clear device_name
dmsetup reload device_name [table_file]
dmsetup rename device_name new_name
dmsetup ls [--target target_type] [--exec command]
dmsetup info [device_name]
dmsetup info -c|-C|--columns [--noheadings] [-o name] [device_name]
dmsetup deps [device_name]
dmsetup status [--target target_type] [device_name]
dmsetup table [--target target_type] [device_name]
dmsetup wait device_name [event_nr]
dmsetup mknodes [device_name]
DESCRIPTIONdmsetup manages logical devices that use the device-mapper driver. Devices are created by loading a table that specifies a target for each sector (512 bytes) in the logical device.
The first argument to dmsetup is a command. The second argument is the logical device name or uuid.
Display output in columns rather than as Field: Value lines.
Specify the major number.
Specify the minor number.
Suppress the headings line when using columnar output.
Tell the kernel not to supply the open reference count for the device.
When creating a device, don't load any table.
Specify which fields to display. Only -o name
Set the table being loaded read-only.
Specify the uuid.
Produce additional output.
Display the library and kernel driver version.
Creates a device with the given name. If table_file is supplied, the table is loaded and made live. Otherwise a table is read from standard input unless --notable is used. The optional uuid can be used in place of device_name in subsequent dmsetup commands. If successful a device will appear as /dev/device-mapper/<device-name>. See below for information on the table format.
Outputs a list of (major, minor) pairs for devices referenced by the live table for the specified device.
Outputs some brief information about the device in the form:
State: SUSPENDED|ACTIVE, READ-ONLY
Tables present: LIVE and/or INACTIVE
Open reference count
Last event sequence number (used by wait)
Major and minor device number
Number of targets in the live table
List device names. Optionally only list devices that have at least one target of the specified type. Optionally execute a command for each device. The device name is appended to the supplied command.
Loads table_file into the inactive table slot for device_name. If table_file is not supplied, reads a table from standard input.
Removes a device. It will no longer be visible to dmsetup and will be deleted when its open_count is zero.
Attempts to remove all device definitions i.e. reset the driver. Use with care!
Renames a device.
Un-suspends a device. If an inactive table has been loaded, it becomes live. Postponed I/O then gets re-queued for processing.
Outputs status information for each of the device's targets. With --target, only information relating to the specified target type is displayed.
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.
Outputs the current table for the device in a format that can be fed back in using the create or load commands. With --target, only information relating to the specified target type is displayed.
Displays the names and versions of the currently-loaded targets.
Outputs version information.
Sleeps until the event counter for device_name exceeds event_nr. Use -v to see the event number returned. To wait until the next event is triggered, use info to find the last event number.
TABLE FORMATEach line of the table specifies a single target and is of the form:
logical_start_sector num_sectors target_type target_args
There are currently three simple target types available together with more complex optional ones that implement snapshots and mirrors.
The traditional linear mapping.
Creates a striped area.
e.g. striped 2 32 /dev/hda1 0 /dev/hdb1 0 will map the first chunk (16k) as follows:
LV chunk 1 -> hda1, chunk 1
LV chunk 2 -> hdb1, chunk 1
LV chunk 3 -> hda1, chunk 2
LV chunk 4 -> hdb1, chunk 2
Errors any I/O that goes to this area. Useful for testing or for creating devices with holes in them.
# A table to join two disks together
0 1028160 linear /dev/hda 0
1028160 3903762 linear /dev/hdb 0
# A table to stripe across the two disks,
# and add the spare space from
# hdb to the back of the volume
0 2056320 striped 2 32 /dev/hda 0 /dev/hdb 0
2056320 2875602 linear /dev/hdb 1028160
AUTHORSOriginal version: Joe Thornber (email@example.com)
SEE ALSODevice-mapper resource page: http://sources.redhat.com/dm/