Device Mapper

6.3.90.900

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Device Mapper

Linux Device Mapper bindings using "libdevmapper.so.1.02".

package: dm

Linux Device Mapper works with mappings and targets.

Every mapping have a named block device in "/dev/mapper" and a table of targets that together represent surface of the block device. For example a mapping "vg_mordae-lv_root" may represent a logical volume that maps 10 GiB of space in the middle of my laptop’s only disk drive using a linear mapping.

procedure
(dm-create name [#:uuid uuid] target ...) → void?
  name : string?
  uuid : (or/c #f string?) = #f
  target : dm-target?

Create new mapping from list of targets. You can supply an uuid or have it automatically generated.

procedure
(dm-reload name target ...) → void?
name : string?
target : dm-target?

Atomically replace table of specified mapping.

procedure
(dm-rename name
new-name
[ #:new-uuid new-uuid]) → void?
  name : string?
  new-name : string?
  new-uuid : (or/c #f string?) = #f

Rename specified mapping, possibly with uuid (if needed).

procedure
(dm-remove name) → void?
name : string?

Destroy specified mapping.

procedure
(dm-get-table name) → (listof dm-target?)
name : string?

Query current table (that is a list of targets) of specified mapping.

struct
(struct dm-target (start length type params)
    #:extra-constructor-name make-dm-target
    #:transparent)
  start : integer?
  length : integer?
  type : symbol?
  params : (listof (or/c string? integer?))

Single row of a device map table. For example when creating a mapping:

(dm-create "test"
(dm-target 0 1024 'linear "253:1" 2048)
(dm-target 1024 1024 'linear "253:2" 2048))

procedure
(dm-list) → (listof string?)

List names of mappings defined on this machine.

procedure
(dm-get-info name) → dm-info?
name : string?

Query information about a mapping.

struct
(struct dm-info ( exists
suspended
live-table
inactive-table
open-count
event-nr
major
minor
read-only
target-count)
    #:extra-constructor-name make-dm-info
    #:transparent)
  exists : boolean?
  suspended : boolean?
  live-table : boolean?
  inactive-table : boolean?
  open-count : integer?
  event-nr : integer?
  major : integer?
  minor : integer?
  read-only : boolean?
  target-count : integer?

Mapping information that can be obtained with dm-get-info.

procedure
(dm-suspend name) → void?
name : string?

Suspend specified mapping, that is: flush pending requests and block new ones.

procedure
(dm-resume name) → void?
name : string?

Cancel suspension of specified mapping.

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