pve-storage-lvm.adoc

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