pve-storage-lvm.adoc

   1 [[storage_lvm]]
   2 LVM Backend
   3 -----------
   4 ifdef::wiki[]
   5 :pve-toplevel:
   6 :title: Storage: LVM
   7 endif::wiki[]
   8
   9 Storage pool type: `lvm`
  10
  11 LVM is a light software layer on top of hard disks and partitions. It
  12 can be used to split available disk space into smaller logical
  13 volumes. LVM is widely used on Linux and makes managing hard drives
  14 easier.
  15
  16 Another use case is to put LVM on top of a big iSCSI LUN. That way you
  17 can easily manage space on that iSCSI LUN, which would not be possible
  18 otherwise, because the iSCSI specification does not define a
  19 management interface for space allocation.
  20
  21
  22 Configuration
  23 ~~~~~~~~~~~~~
  24
  25 The LVM backend supports the common storage properties `content`, `nodes`,
  26 `disable`, and the following LVM specific properties:
  27
  28 `vgname`::
  29
  30 LVM volume group name. This must point to an existing volume group.
  31
  32 `base`::
  33
  34 Base volume. This volume is automatically activated before accessing
  35 the storage. This is mostly useful when the LVM volume group resides
  36 on a remote iSCSI server.
  37
  38 `saferemove`::
  39
  40 Zero-out data when removing LVs. When removing a volume, this makes
  41 sure that all data gets erased and cannot be accessed by other LVs
  42 created later (which happen to be assigned the same physical extents).
  43 This is a costly operation, but may be required as a security measure
  44 in certain environments.
  45
  46 `saferemove_throughput`::
  47
  48 Wipe throughput (`cstream -t` parameter value).
  49
  50 .Configuration Example (`/etc/pve/storage.cfg`)
  51 ----
  52 lvm: myspace
  53         vgname myspace
  54         content rootdir,images
  55 ----
  56
  57 File naming conventions
  58 ~~~~~~~~~~~~~~~~~~~~~~~
  59
  60 The backend use basically the same naming conventions as the ZFS pool
  61 backend.
  62
  63  vm-<VMID>-<NAME>      // normal VM images
  64
  65 Storage Features
  66 ~~~~~~~~~~~~~~~~
  67
  68 LVM is a typical block storage, but this backend does not support
  69 snapshots and clones. Unfortunately, normal LVM snapshots are quite
  70 inefficient, because they interfere with all writes on the entire volume
  71 group during snapshot time.
  72
  73 One big advantage is that you can use it on top of a shared storage,
  74 for example, an iSCSI LUN. The backend itself implements proper cluster-wide
  75 locking.
  76
  77 TIP: The newer LVM-thin backend allows snapshots and clones, but does
  78 not support shared storage.
  79
  80
  81 .Storage features for backend `lvm`
  82 [width="100%",cols="m,m,3*d",options="header"]
  83 |==============================================================================
  84 |Content types  |Image formats  |Shared   |Snapshots |Clones
  85 |images rootdir |raw            |possible |no        |no
  86 |==============================================================================
  87
  88 Examples
  89 ~~~~~~~~
  90
  91 List available volume groups:
  92
  93  # pvesm lvmscan
  94
  95 ifdef::wiki[]
  96
  97 See Also
  98 ~~~~~~~~
  99
 100 * link:/wiki/Storage[Storage]
 101
 102 endif::wiki[]
 103
 104