pve-storage-dir.adoc

   1 Directory Backend
   2 -----------------
   3 include::attributes.txt[]
   4
   5 Storage pool type: `dir`
   6
   7 {pve} can use local directories or locally mounted shares for
   8 storage. A directory is a file level storage, so you can store any
   9 content type like virtual disk images, containers, templates, ISO images
  10 or backup files.
  11
  12 NOTE: You can mount additional storages via standard linux '/etc/fstab',
  13 and then define a directory storage for that mount point. This way you
  14 can use any file system supported by Linux.
  15
  16 This backend assumes that the underlying directory is POSIX
  17 compatible, but nothing else. This implies that you cannot create
  18 snapshots at the storage level. But there exists a workaround for VM
  19 images using the `qcow2` file format, because that format supports
  20 snapshots internally.
  21
  22 TIP: Some storage types do not support `O_DIRECT`, so you can't use
  23 cache mode `none` with such storages. Simply use cache mode
  24 `writeback` instead.
  25
  26 We use a predefined directory layout to store different content types
  27 into different sub-directories. This layout is used by all file level
  28 storage backends.
  29
  30 .Directory layout
  31 [width="100%",cols="d,m",options="header"]
  32 |===========================================================
  33 |Content type        |Subdir
  34 |VM images           |images/<VMID>/
  35 |ISO images          |template/iso/
  36 |Container templates |template/cache
  37 |Backup files        |dump/
  38 |===========================================================
  39
  40 Configuration
  41 ~~~~~~~~~~~~~
  42
  43 This backend supports all common storage properties, and adds an
  44 additional property called `path` to specify the directory. This
  45 needs to be an absolute file system path.
  46
  47 .Configuration Example ('/etc/pve/storage.cfg')
  48 ----
  49 dir: backup
  50         path /mnt/backup
  51         content backup
  52         maxfiles 7
  53 ----
  54
  55 Above configuration defines a storage pool called `backup`. That pool
  56 can be used to store up to 7 backups (`maxfiles 7`) per VM. The real
  57 path for the backup files is '/mnt/backup/dump/...'.
  58
  59
  60 File naming conventions
  61 ~~~~~~~~~~~~~~~~~~~~~~~
  62
  63 This backend uses a well defined naming scheme for VM images:
  64
  65  vm-<VMID>-<NAME>.<FORMAT>
  66
  67 `<VMID>`::
  68
  69 This specifies the owner VM.
  70
  71 `<NAME>`::
  72
  73 This can be an arbitrary name (`ascii`) without white spaces. The
  74 backend uses `disk-[N]` as default, where `[N]` is replaced by an
  75 integer to make the name unique.
  76
  77 `<FORMAT>`::
  78
  79 Species the image format (`raw|qcow2|vmdk`).
  80
  81 When you create a VM template, all VM images are renamed to indicate
  82 that they are now read-only, and can be uses as a base image for clones:
  83
  84  base-<VMID>-<NAME>.<FORMAT>
  85
  86 NOTE: Such base images are used to generate cloned images. So it is
  87 important that those files are read-only, and never get modified. The
  88 backend changes the access mode to `0444`, and sets the immutable flag
  89 (`chattr +i`) if the storage supports that.
  90
  91 Storage Features
  92 ~~~~~~~~~~~~~~~~
  93
  94 As mentioned above, most file systems do not support snapshots out
  95 of the box. To workaround that problem, this backend is able to use
  96 `qcow2` internal snapshot capabilities.
  97
  98 Same applies to clones. The backend uses the `qcow2` base image
  99 feature to create clones.
 100
 101 .Storage features for backend `dir`
 102 [width="100%",cols="m,m,3*d",options="header"]
 103 |==============================================================================
 104 |Content types                     |Image formats         |Shared |Snapshots |Clones
 105 |images rootdir vztempl iso backup |raw qcow2 vmdk subvol |no     |qcow2     |qcow2
 106 |==============================================================================
 107
 108
 109 Examples
 110 ~~~~~~~~
 111
 112 Please use the following command to allocate a 4GB image on storage `local`:
 113
 114  # pvesm alloc local 100 vm-100-disk10.raw 4G
 115  Formatting '/var/lib/vz/images/100/vm-100-disk10.raw', fmt=raw size=4294967296
 116  successfully created 'local:100/vm-100-disk10.raw'
 117
 118 NOTE: The image name must conform to above naming conventions.
 119
 120 The real file system path is shown with:
 121
 122  # pvesm path local:100/vm-100-disk10.raw
 123  /var/lib/vz/images/100/vm-100-disk10.raw
 124
 125 And you can remove the image with:
 126
 127  # pvesm free local:100/vm-100-disk10.raw
 128
 129
 130 ifdef::wiki[]
 131
 132 See Also
 133 ~~~~~~~~
 134
 135 * link:/wiki/Storage[Storage]
 136
 137 endif::wiki[]
 138
 139