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133 lines
2.8 KiB
Groff
133 lines
2.8 KiB
Groff
.TH DMSETUP 8 "Nov 29 2001" "Linux" "MAINTENTANCE 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 create
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.I device_name table_file
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.br
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.B dmsetup remove
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.I device_name
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.br
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.B dmsetup suspend
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.I device_name
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.br
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.B dmsetup resume
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.I device_name
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.br
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.B dmsetup reload
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.I device_name table_file
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.br
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.B dmsetup info
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.I device_name
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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 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.
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.SH COMMANDS
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.IP \fBcreate
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.I device_name table_file
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.br
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Attempts to create a device using the table file given. If
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successful a device will appear as
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/dev/device-mapper/<device-name>. See below for information
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on the table file format.
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.IP \fBremove
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.I device_name
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.br
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Removes the device
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.IP \fBsuspend
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.I device_name
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.br
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Suspends a device. Any I/O that has already been mapped by the device
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but has not yet completed will be flushed. Any further I/O to that
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device will be postponed for as long as the device is suspended.
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.IP \fBresume
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.I device_name
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.br
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Un-suspends a device. Postponed I/O now gets re-queued for processing.
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.IP \fBreload
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.I device_name table_file
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.br
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This command will only work if a device is in the suspended state.
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It changes the mapping table for an existing device.
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.IP \fBinfo
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.I 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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.br
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SUSPENDED|ACTIVE
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.br
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open_count
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.br
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major,minor
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.br
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target_count
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.SH TABLE FORMAT
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Each line of the table specifies a single target and is of the form:
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.br
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logical_start_sector num_sectors target_type target_args
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.br
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.br
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At the moment there are 3 simple target types available - though your
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system might have more in the form of modules.
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.IP \fBlinear
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.I destination_device start_sector
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.br
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The traditional linear mapping.
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.IP \fBstriped
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.I num_stripes chunk_size [destination start_sector]+
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.br
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Creates a striped area.
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.br
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e.g. striped 2 32 /dev/hda1 0 /dev/hdb1 0
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will map the first chunk (16k) as follows:
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.br
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LV chunk 1 -> hda1, chunk 1
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.br
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LV chunk 2 -> hdb1, chunk 1
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.br
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LV chunk 3 -> hda1, chunk 2
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.br
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LV chunk 4 -> hdb1, chunk 2
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.br
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etc.
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.IP \fBio-err
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.br
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Errors any I/O that goes to this area. Useful for testing or
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for creating devices with holes in them.
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.SH EXAMPLES
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# A table to join two disks together
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.br
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.br
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0 1028160 linear /dev/hda 0
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.br
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1028160 3903762 linear /dev/hdb 0
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# A table to stripe across the two disks,
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.br
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# and add the spare space from
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.br
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# hdb to the back of the volume
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0 2056320 striped 2 32 /dev/hda 0 /dev/hdb 0
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.br
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2056320 2875602 linear /dev/hdb 1028160
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.SH AUTHORS
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Original version: Joe Thornber (thornber@sistina.com)
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