pve-storage-dir.adoc

   1 [[storage_directory]]
   2 Directory Backend
   3 -----------------
   4 ifdef::wiki[]
   5 :pve-toplevel:
   6 :title: Storage: Directory
   7 endif::wiki[]
   8
   9 Storage pool type: `dir`
  10
  11 {pve} can use local directories or locally mounted shares for
  12 storage. A directory is a file level storage, so you can store any
  13 content type like virtual disk images, containers, templates, ISO images
  14 or backup files.
  15
  16 NOTE: You can mount additional storages via standard linux `/etc/fstab`,
  17 and then define a directory storage for that mount point. This way you
  18 can use any file system supported by Linux.
  19
  20 This backend assumes that the underlying directory is POSIX
  21 compatible, but nothing else. This implies that you cannot create
  22 snapshots at the storage level. But there exists a workaround for VM
  23 images using the `qcow2` file format, because that format supports
  24 snapshots internally.
  25
  26 TIP: Some storage types do not support `O_DIRECT`, so you can't use
  27 cache mode `none` with such storages. Simply use cache mode
  28 `writeback` instead.
  29
  30 We use a predefined directory layout to store different content types
  31 into different sub-directories. This layout is used by all file level
  32 storage backends.
  33
  34 .Directory layout
  35 [width="100%",cols="d,m",options="header"]
  36 |===========================================================
  37 |Content type        |Subdir
  38 |VM images           |`images/<VMID>/`
  39 |ISO images          |`template/iso/`
  40 |Container templates |`template/cache/`
  41 |Backup files        |`dump/`
  42 |Snippets            |`snippets/`
  43 |===========================================================
  44
  45
  46 Configuration
  47 ~~~~~~~~~~~~~
  48
  49 This backend supports all common storage properties, and adds an
  50 additional property called `path` to specify the directory. This
  51 needs to be an absolute file system path.
  52
  53 .Configuration Example (`/etc/pve/storage.cfg`)
  54 ----
  55 dir: backup
  56         path /mnt/backup
  57         content backup
  58         maxfiles 7
  59 ----
  60
  61 Above configuration defines a storage pool called `backup`. That pool
  62 can be used to store up to 7 backups (`maxfiles 7`) per VM. The real
  63 path for the backup files is `/mnt/backup/dump/...`.
  64
  65
  66 File naming conventions
  67 ~~~~~~~~~~~~~~~~~~~~~~~
  68
  69 This backend uses a well defined naming scheme for VM images:
  70
  71  vm-<VMID>-<NAME>.<FORMAT>
  72
  73 `<VMID>`::
  74
  75 This specifies the owner VM.
  76
  77 `<NAME>`::
  78
  79 This can be an arbitrary name (`ascii`) without white space. The
  80 backend uses `disk-[N]` as default, where `[N]` is replaced by an
  81 integer to make the name unique.
  82
  83 `<FORMAT>`::
  84
  85 Specifies the image format (`raw|qcow2|vmdk`).
  86
  87 When you create a VM template, all VM images are renamed to indicate
  88 that they are now read-only, and can be used as a base image for clones:
  89
  90  base-<VMID>-<NAME>.<FORMAT>
  91
  92 NOTE: Such base images are used to generate cloned images. So it is
  93 important that those files are read-only, and never get modified. The
  94 backend changes the access mode to `0444`, and sets the immutable flag
  95 (`chattr +i`) if the storage supports that.
  96
  97
  98 Storage Features
  99 ~~~~~~~~~~~~~~~~
 100
 101 As mentioned above, most file systems do not support snapshots out
 102 of the box. To workaround that problem, this backend is able to use
 103 `qcow2` internal snapshot capabilities.
 104
 105 Same applies to clones. The backend uses the `qcow2` base image
 106 feature to create clones.
 107
 108 .Storage features for backend `dir`
 109 [width="100%",cols="m,m,3*d",options="header"]
 110 |==============================================================================
 111 |Content types                              |Image formats         |Shared |Snapshots |Clones
 112 |images rootdir vztmpl iso backup snippets  |raw qcow2 vmdk subvol |no     |qcow2     |qcow2
 113 |==============================================================================
 114
 115
 116 Examples
 117 ~~~~~~~~
 118
 119 Please use the following command to allocate a 4GB image on storage `local`:
 120
 121  # pvesm alloc local 100 vm-100-disk10.raw 4G
 122  Formatting '/var/lib/vz/images/100/vm-100-disk10.raw', fmt=raw size=4294967296
 123  successfully created 'local:100/vm-100-disk10.raw'
 124
 125 NOTE: The image name must conform to above naming conventions.
 126
 127 The real file system path is shown with:
 128
 129  # pvesm path local:100/vm-100-disk10.raw
 130  /var/lib/vz/images/100/vm-100-disk10.raw
 131
 132 And you can remove the image with:
 133
 134  # pvesm free local:100/vm-100-disk10.raw
 135
 136
 137 ifdef::wiki[]
 138
 139 See Also
 140 ~~~~~~~~
 141
 142 * link:/wiki/Storage[Storage]
 143
 144 endif::wiki[]
 145
 146