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.
  42
  43 `saferemove_throughput`::
  44
  45 Wipe throughput (`cstream -t` parameter value).
  46
  47 .Configuration Example (`/etc/pve/storage.cfg`)
  48 ----
  49 lvm: myspace
  50         vgname myspace
  51         content rootdir,images
  52 ----
  53
  54 File naming conventions
  55 ~~~~~~~~~~~~~~~~~~~~~~~
  56
  57 The backend use basically the same naming conventions as the ZFS pool
  58 backend.
  59
  60  vm-<VMID>-<NAME>      // normal VM images
  61
  62 Storage Features
  63 ~~~~~~~~~~~~~~~~
  64
  65 LVM is a typical block storage, but this backend does not support
  66 snapshots and clones. Unfortunately, normal LVM snapshots are quite
  67 inefficient, because they interfere with all writes on the entire volume
  68 group during snapshot time.
  69
  70 One big advantage is that you can use it on top of a shared storage,
  71 for example, an iSCSI LUN. The backend itself implements proper cluster-wide
  72 locking.
  73
  74 TIP: The newer LVM-thin backend allows snapshots and clones, but does
  75 not support shared storage.
  76
  77
  78 .Storage features for backend `lvm`
  79 [width="100%",cols="m,m,3*d",options="header"]
  80 |==============================================================================
  81 |Content types  |Image formats  |Shared   |Snapshots |Clones
  82 |images rootdir |raw            |possible |no        |no
  83 |==============================================================================
  84
  85 Examples
  86 ~~~~~~~~
  87
  88 List available volume groups:
  89
  90  # pvesm lvmscan
  91
  92 ifdef::wiki[]
  93
  94 See Also
  95 ~~~~~~~~
  96
  97 * link:/wiki/Storage[Storage]
  98
  99 endif::wiki[]
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