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 

With the latest feature of qemu, the disk can be shrinked. Ref link: 

Does VDSM have any plan for this?


Xiaozhen Qi
Huawei Technologies Co.,LTD.
IT Product Line CloudOS PDU
China, Xi'an
Mobile: +86-13609283376
Email: qixiaoz...@huawei.com
vdsm-devel mailing list

Reply via email to