On 01/13/2014 04:19 AM, Qixiaozhen wrote:
Hi,all
VDSM have realized the feature of thin provision in its released version.
Volumes have 2 major properties:
1.*type*- How are the bits written to the underlying volume.
o/raw/- means a simple raw access a write to offset X will be written on
offset X
o/qcow2/- means that the storage will be accessed as a qcow2 image and
all that this entails
2.*allocation*- How should VDSM allocated the storage
o/preallocated/- VDSM will try it's best to guaranty that all the
storage that was requested is allocated right away. Some storage
configuration may render preallocation pointless.
o/sparse/thin provision/- space will be allocated for the volume as needed
As is known to all, thin provision means allocating the disk space once
the instance writes the data on the area of volume in the first time.
The size of the disk will be increasing even though we have deleted the
file in the instance.
With the latest feature of qemu, the disk can be shrinked. Ref link:
http://dustymabe.com/2013/06/11/recover-space-from-vm-disk-images-by-using-discardfstrim/
Does VDSM have any plan for this?
we have a long list of features folks are interested in. please open a
bugzilla RFE if you are interested in this feature.
of course, we would be more than happy if you would like to try and
collaborate on implementing this.
please note while this may work for NFS, it may require extra work for
iscsi which uses an LV which may have to be shrinked as well.
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