[ovirt-users] difference between thin/depentend and clone/dependent vm virtual machine

[Michal Skrivanek]

On Apr 17, 2014, at 16:43 , Tamer Lima <tamer.americo at gmail.com> wrote:

> hi,  thanks for reply
> 
> I am investigating what is and how "thin virtualization" works
> 
> Do you know if  HADOOP is indicated to work under "thin" environment ?
> On Hadoop I will put large workloads  and this  thin virtualization  utilizes more resources than exists (shareable environment)
> that is,
> if I have a real physical necessity of 500gb for each hadoop host  and my Thin Virtualization has  2TB on NFS,  I can have only 4 virtual machines  (500GB each), or less.
> 
> For this case I believe clone virtual machine is the right choice. But in my environment it takes 1h30m to build one cloned virtual machine.

if you plan to overcommit then go with thin. The drawback is that if you of course hit the physical limit the VMs will run out of space...
if you plan to allocate 500GB each, consume all of it, never plan to grow then go with the "clone"….yes, it's going to take time to write all that stuff. With "thin" you need to do the same amount of writes, but gradually over time while you're allocating it it

hope it helps

Thanks,
michal

> 
> 
> 
> Am I correct ?
> 
> 
> 
>   
> 
> On Thu, Apr 17, 2014 at 7:33 AM, Michal Skrivanek <michal.skrivanek at redhat.com> wrote:
> 
> On Apr 16, 2014, at 16:41 , Tamer Lima <tamer.americo at gmail.com> wrote:
> 
> >
> >
> > Hello,
> >
> > I created VMs by two ways :
> >
> > 1)  on tab virtual machines > new vm  > template (centos_65_64bits)
> > 1.1 configuration : I do not select stateless checkbox
> > 1.2 this process takes a 1h30 to create each machine.
> >
> > 2)  on tab pools > new vm  > template (centos_65_64bits)
> > 2.1 default configuration : stateless
> > 2.2 Here I created 3 virtual machines at once
> > 2.3 this process takes only one minute
> >
> > On the tab virtual machines I can see all virtual machines.
> > Pooled machines have different icon image
> > and description is different too:
> >
> > machines generated from tab VM  are described as clone/dependent
> > - clone is a phisical copy?
> > machines generated from tab POOL are described as thin/independent
> > - thin is a just a  reference to template vm ? what is phisical? any configuration file?
> 
> yeah, sort of.
> just google thin provisioning in general:)
> 
> 
> >
> >
> > In practice, what is the difference between these machines ?
> >
> >
> >
> >
> > http://www.ovirt.org/Features/PrestartedVm
> > "Today there are 2 types of Vm pools:
> >       • Manual - the Vm is supposed to be manually returned to the pool. In practice, this is not really entirely supported.
> >       • Automatic - once the user shuts down the Vm - it returns to the pool (stateless)."
> >
> >  all vm created from pool  are stateless ?
> 
> the automatic pool, yes
> 
> Thanks,
> michal
> 
> >
> >
> > thanks
> >
> >
> >
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> 
>