Resource pools

[Guv]

I am trying to understand what happens to a resource pool when a virtual machine is removed from a resource pool, how does it affect its shares associated with the resource pool, do they stay the same, increase or decrease, or does it affect if there was a custom value.

I read the vmware documenation which says when you remove a VM from a resource pool, the total number of shares associated with the resouce pool decreases, so that each remianing share represents more resources.

I dont get this, shouldnt the total number of shares increase when the VM is removed.

Any explanantion on this.

[opbz]

hi

as I understand resource pools the values do not change when you add VMs to one.

That leads me to believe that they wont change when you remove a VM from it.

Basically wen you add a VM to a resouce pool the shares of the VM do not change they are just applied against the resource pool values.

Have a look at this documetn its for Esx 3.5 but its pretty good

http://www.vmware.com/pdf/vi3_35/esx_3/r35u2/vi3_35_25_u2_resource_mgmt.pdf

[weinstein5]

Think of it this way - if you have 5 VMs in contention in the resource pool with equal shares the resources will be divided equally amongst all 5 ot each will get 20% - when you remove one of those VMs now there are 4 and the reources will still be divided equally so each will get 25% of the resource assigned to the pool -

[frankdenneman]

Guv,

The amount of shares issued to the resource pool is not related to the amount of child virtual machines or child resource pool running inside the resource pool. The resource pools compete for resources with its siblings based on its resource allocation settings (reservation, shares and limits). After receiving the amount of resources, the resource pool will divide its resources amongst its child virtual machine and child resource pools.

By default 0 shares are active inside the resource pool, when adding virtual machines, the amount of shares issued increases. If the amount of shares increases the value of the shares are diluted, because the amount of resources provided by the resource pool stay the same. For example, when dividing 1000 MHz of CPU between 1000 shares, each share has an equal value of 1 MHz. If 1000 shares are issued, because a second VM is added, the 1000 MHz of CPU must be divided between 2000 shares, which dilutes the share value to 0.5 MHz. If 5 VM's are active, each owning 1000 shares, the MHz per share value equals 0.2 MHz, when removing one virtual machine with 1000 shares, a 1000 shares are removed, decreasing the amount of shares inside the resource pool to 4000 and increasing the MHz per share value to 0.25. Remember the entire time the parent resource pool competes with its siblings for resources with its own share values.

When comparing this to the movie Inception, RP's competing with other siblings is happening in the first dream, where child-objects competing with other child-objects for the resources of its parent RP are happening in the dream within the dream. I bet the script writers of inception looked at a complex resource pool hierarchy when writing the script

Frank Denneman

http://frankdenneman.nl

@frankdenneman

Co-author: vSphere 4.1 HA and DRS technical Deepdive

[djak44]

Therefore the number od shares will decrease, because as you stated it starts with zero shares and if we remove all added VM's it goes back to zero. Is this correct?

Regards,

Djamel