X-Git-Url: https://git.proxmox.com/?p=pve-docs.git;a=blobdiff_plain;f=pvesm.adoc;h=5f8020e895a4ebdd5aee5a35cfaee4004d4f421d;hp=36be46e87948dc260f02e72988818ee42a72275e;hb=9c41b54dc509727c2c8d77129a9b8dbbdf03e7fd;hpb=deb4673f279adea9069596f64fb70ff3f0e88302 diff --git a/pvesm.adoc b/pvesm.adoc index 36be46e..5f8020e 100644 --- a/pvesm.adoc +++ b/pvesm.adoc @@ -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 --------------------- @@ -109,24 +134,33 @@ Each storage pool has a ``, and is uniquely identified by its `: ` line starts the pool definition, which is then 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. +To be more specific, take a look at the default storage configuration +after installation. It contains one special local storage pool named +`local`, which refers to the directory '/var/lib/vz' and is always +available. The {pve} installer creates additional storage entries +depending on the storage type chosen at installation time. + .Default storage configuration ('/etc/pve/storage.cfg') ---- dir: local path /var/lib/vz content iso,vztmpl,backup +# default image store on LVM based installation lvmthin: local-lvm thinpool data vgname pve content rootdir,images + +# default image store on ZFS based installation +zfspool: local-zfs + pool rpool/data + sparse + content images,rootdir ---- Common Storage Properties