Hi, NFS will be sparse. Preallocate is relevant for block storage.
There is a fix to change the UI to display the format (RAW/QCOW2) of the disk instead of the type (Sparse/Preallocated) [1]. When creating a VM from a template, If you choose thin provisioning the disk format will be alway QCOW2, keeping the disk from the template as is read-only and creating a disk only for the diffs. If you choose Clone, then the whole disk will be copied and you will have a new copy of template disk in whatever format you want (Raw or QCOW2). >What happens if you clone a source VM which is using "thin" ? The VM cloned from a thin templated base VM will be created with a full copy of the disk (as in "Clone" when creating from template) >Interesting. Is there a way to "merge" the changes ? (I mean to change it from being "thin provision" after its creation and make it an independent VM) No, a VM created as thin will remain like that. You can clone a new VM from it and them you will have an "independent VM" >When you create a template for the first time, it seems you can't choose between clone and thin, which one is used ? When you create a template you make a read-only copy of the VM disks (Clone) . You can choose the format of the disks (RAW/QCOW2) [1] https://gerrit.ovirt.org/#/c/57190/ On Mon, May 23, 2016 at 3:50 PM, Alexis HAUSER < [email protected]> wrote: > >Regarding your examples, I cannot say exactly because of lack of some > >details. What storage type are you using? How do you measure the space > used > >on the physical disk? > > > simply df -h on the PC sharing the NFS storage. > > > >> For example, when making a VM from template, using pre-allocated disk > >> option, for a 50GB Virtual disk, it only uses 3GB on the physical disk. > > > 3GB is the VM's disk? What about the disk of the template? > > > 3GB is the difference using df -h betweem before making the template, and > after making it and running the VM. > > > >Generally, 50GB pre-allocated disk will take 50GB of physical space. A > 50GB > >sparse disk will take as many 1GB chunks as needed to store all the > >information that was written to it, maximum 50GB. > > > so "pre-allocated" doesn't use pre-allocation but sparse instead ? I don't > really get it, sorry. > > > >When you create a VM by cloning another VM or create a VM from a template > >in "clone" mode, a copy of the source disk will be created. The new disk > >will take as much space as the source disk did. > > > What happens if you clone a source VM which is using "thin" ? > > > >When you create a VM from a template in "thin provision" mode or creating > a > >VM in a pool, the new disk will be initially only a reference to the > source > >disk. Reading from it will read the source disk. Writing to it will write > >to the new disk, not touching the source. Thus, all disk fragments that > >were overwritten after disk creation will be physically stored in the new > >disk and read from it, those that were not overwritten, will be read from > >the source disk. > > > Interesting. Is there a way to "merge" the changes ? (I mean to change it > from being "thin provision" after its creation and make it an independent > VM) > When you create a template for the first time, it seems you can't choose > between clone and thin, which one is used ? > _______________________________________________ > Users mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/users >
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