pve-storage-dir.adoc

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