pve-storage-dir.adoc

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