pve-storage-lvm.adoc

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