add warning about over-provisioning

[pve-docs.git] / pvesm.adoc

diff --git a/pvesm.adoc b/pvesm.adoc
index 90ae8505179501de4f9ca9b82a93d4b0e8abe843..462d9427c1965ecb2260c3a100adf03dd9541eb8 100644 (file)
--- a/pvesm.adoc
+++ b/pvesm.adoc
@@ -71,7 +71,7 @@ snapshots and clones.
 |NFS            |nfs         |file  |yes   |no       |yes
 |GlusterFS      |glusterfs   |file  |yes   |no       |yes
 |LVM            |lvm         |block |no    |no       |yes
-|LVM-thin       |lvmthin     |block |no    |yes      |beta
+|LVM-thin       |lvmthin     |block |no    |yes      |yes
 |iSCSI/kernel   |iscsi       |block |yes   |no       |yes
 |iSCSI/libiscsi |iscsidirect |block |yes   |no       |yes
 |Ceph/RBD       |rbd         |block |yes   |yes      |yes
@@ -83,6 +83,31 @@ snapshots and clones.
 TIP: It is possible to use LVM on top of an iSCSI storage. That way
 you get a 'shared' LVM storage.
 
+Thin provisioning
+~~~~~~~~~~~~~~~~~
+
+A number of storages, and the Qemu image format `qcow2`, support _thin
+provisioning_.  With thin provisioning activated, only the blocks that
+the guest system actually use will be written to the storage.
+
+Say for instance you create a VM with a 32GB hard disk, and after
+installing the guest system OS, the root filesystem of the VM contains
+3 GB of data.  In that case only 3GB are written to the storage, even
+if the guest VM sees a 32GB hard drive. In this way thin provisioning
+allows you to create disk images which are larger than the currently
+available storage blocks. You can create large disk images for your
+VMs, and when the need arises, add more disks to your storage without
+resizing the VMs filesystems.
+
+All storage types which have the 'Snapshots' feature also support thin
+provisioning.
+
+CAUTION: If a storage runs full, all guests using volumes on that
+storage receives IO error. This can cause file system inconsistencies
+and may corrupt your data. So it is advisable to avoid
+over-provisioning of your storage resources, or carefully observe
+free space to avoid such conditions.
+
 Storage Configuration
 ---------------------
 
@@ -118,12 +143,16 @@ followed by a list of properties. Most properties have values, but some of
 them come with reasonable default. In that case you can omit the value.
 
 .Default storage configuration ('/etc/pve/storage.cfg')
-====
- dir: local
+----
+dir: local
        path /var/lib/vz
-       content backup,iso,vztmpl,images,rootdir
-       maxfiles 3
-====
+       content iso,vztmpl,backup
+
+lvmthin: local-lvm
+       thinpool data
+       vgname pve
+       content rootdir,images
+----
 
 Common Storage Properties
 ~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -304,6 +333,34 @@ Show filesystem path for a volume
 
  pvesm path <VOLUME_ID>
 
+ifdef::wiki[]
+
+See Also
+--------
+
+* link:/index.php/Storage:_Directory[Storage: Directory]
+
+* link:/index.php/Storage:_GlusterFS[Storage: GlusterFS]
+
+* link:/index.php/Storage:_User_Mode_iSCSI[Storage: User Mode iSCSI]
+
+* link:/index.php/Storage:_iSCSI[Storage: iSCSI]
+
+* link:/index.php/Storage:_LVM[Storage: LVM]
+
+* link:/index.php/Storage:_LVM_Thin[Storage: LVM Thin]
+
+* link:/index.php/Storage:_NFS[Storage: NFS]
+
+* link:/index.php/Storage:_RBD[Storage: RBD]
+
+* link:/index.php/Storage:_ZFS[Storage: ZFS]
+
+
+endif::wiki[]
+
+ifndef::wiki[]
+
 // backend documentation
 
 include::pve-storage-dir.adoc[]
@@ -316,6 +373,8 @@ include::pve-storage-zfspool.adoc[]
 
 include::pve-storage-lvm.adoc[]
 
+include::pve-storage-lvmthin.adoc[]
+
 include::pve-storage-iscsi.adoc[]
 
 include::pve-storage-iscsidirect.adoc[]
@@ -323,7 +382,10 @@ include::pve-storage-iscsidirect.adoc[]
 include::pve-storage-rbd.adoc[]
 
 
+
 ifdef::manvolnum[]
 include::pve-copyright.adoc[]
 endif::manvolnum[]
 
+endif::wiki[]
+