From ebc15cbca7de277cb3b49244edb9aa7a80413d40 Mon Sep 17 00:00:00 2001 From: Emmanuel Kasper Date: Wed, 18 May 2016 14:52:24 +0200 Subject: [PATCH 1/1] Add chapter for thin provisioning --- pvesm.adoc | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/pvesm.adoc b/pvesm.adoc index 36be46e..8bf043e 100644 --- a/pvesm.adoc +++ b/pvesm.adoc @@ -83,6 +83,23 @@ 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. + Storage Configuration --------------------- -- 2.39.2