Cluster Resource allocations

Anyone to explain the meaning of those columns in Resource Allocations? some of them are clear , but some not , especially ones that are related to the shares.

I also want to know if I reserve X MBytes memory for a VM, how would I know if I am violating the HA policy….I mean there would be not enough resources for HA failover to occur ?

Thanks
jskfanAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)Connect With a Mentor VMware and Virtualization ConsultantCommented:
No, you would need to increase the memory of the VM, and then create a reservation.

You cannot reserve more than what has been set for the current RAM requirements.
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Andrew Hancock (VMware vExpert / EE MVE^2)Connect With a Mentor VMware and Virtualization ConsultantCommented:
You would violate a HA Policy, if the remaining hosts in the Cluster, did not have enough RAM (Memory) available to satisft all your Reservations.

A Memory Reservation is a GUARANTEED RING FENCE resource for that VM.

So if you gave it a reservation of 64GB, and your hosts had a total memory of 64GB per Host, this would violate the HA Policy.

Do you need to use Memory Reservations?
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jskfanAuthor Commented:
Sometimes Resource Allocation is already setup by previous Admins,
I want to know the meaning of those columns, and where to check to make sure that HA failover is not violated…..
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Can you upload a screenshot, and put question marks, around the columns, you need explaining?
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jskfanAuthor Commented:
I believe VMHA has admission control that detects if resource reservation are respected

ha
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
So you would like to know, what all these columns mean?

This is a large topic area, and rather than me cut and paste, the information you require can be found in this document

from Page 13, Chapter 2 - Configuring Resource Allocation
Settings

vSphere Resource Management
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jskfanAuthor Commented:
Columns related to Share /Shares, what do they represent ?
and worst case allocation column
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Shares relate to "pieces" of a cake, the more cake/shares you get the higher priorty the VM get resources, when competing for resources. (e.g. when many VMs are competing for resources)

http://vmzare.wordpress.com/2007/02/27/sharesreservationlimits-cpumemory-resource-settings/

Worst Case, is what is predicted to be the resources your VM will get, based on all the other VMs, allocations.

VMware defines it as:-

Worst Case Allocation
      
The amount of memory resources allocated to the virtual machine based on user-configured resource allocation policies (for example, reservation, shares and limit), and with the assumption that all virtual machines in the cluster consume their full amount of allocated resources.

Source
http://pubs.vmware.com/vsphere-4-esx-vcenter/index.jsp?topic=/com.vmware.vsphere.resourcemanagement.doc_41/getting_started_with_resource_management/c_virtual_machine_resource_allocation_tab.html
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jskfanAuthor Commented:
The columns Reservation and Shares(High,Normal,low,etc..) can be determined, but the Shares value, percent share , I am not sure how you can determine the values, in other words based on what factors , you set up share value to 5000 or to 80%
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jskfanAuthor Commented:
I also want to understand, if the provisioned Memory size for a VM is 4GB ,but under Reservation MB , at the ESX host level(Resource Allocation), you give the same VM 1GB…
Would the actual size of the VM be 5GB RAM  or 4-1=3 GB of RAM?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
If you give a memory reservation of 1GB, this memory is guaranteed! The VM will always get 1GB allocated.

The Total Size will always be 4GB, but with 1GB reserved.
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jskfanAuthor Commented:
And you cannot reserve more than what has been assigned(4gb)?
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jskfanAuthor Commented:
Thank you
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