And I do use memory over-commit
One of the most ridiculous things that Microsoft are saying as of late is that the feature in vSphere that allows you to over commit memory, is not such a big thing and that most people do not use it anyway - here here and here.
If you saw my previous post you will see that I managed to double the amount of virtual machines running on the same host (from 8 to 16 VM's running Windows 2003 Server 1GB RAM) without changing the 8GB RAM configuration on the host.
Would I be able to do this with Hyper-V? Hell No!
So I will say this again to Microsoft. Customers use Memory over-commit, they use it daily, and use it all the time. As long as you do not have this feature - this will be a strong point against using your product.
Enough said about that!
Comments (3)
24/9/09 09:19
Hi Maish,
On the contrary, I think memory oversubscription is a big thing, and a great feature! In my article that you reference, I clearly point that out, however, to compensate for not having the capability, the only option is to add more RAM to the box.
In terms of customers using Memory Oversubscription, not everyone is using it, as denoted by this post on the VMware Virtual Reality blog: http://blogs.vmware.com/virtualreality/2008/10/memory-overcomm.html. Don't get me wrong, what ESX does with memory is incredibly clever, and has some significant benefits, however, not everyone is comfortable with it, and thus, not everyone uses it. Those who are comfortable with it, and understand it, will use it, and I'm sure they will love it!
Matt
24/9/09 10:09
Thank you very much for your comments Matt.
It is nice to see that Microsoft is finally accepting that this feature is something that Virtualization customers want and need.
But sometimes doubling the RAM in the server is not a viable option, cost-wise and because of the limitations on the number of slots.
Granted, that today, most new servers have 16 slots for RAM, so that will not be much of an issue.
24/9/09 10:50
Hi Maish,
You are correct - If a customer already had a server in the business, with a full 16 slots of RAM Dimms, of say, 1GB in size, they have 2 options - they either use Oversubscription of memory, to get more out of what they currently have, or, they replace those 1GB Dimms, with 2GB, or 4GB (8GB Dimms are quite expensive!) and get that server up to 64GB for example. Whilst RAM is cheap, there are arguments for and against both approaches.
I guess on new servers, that a lot of customers will purchase to start their virtualisation journey, I guess they have a choice - RAM or Oversubscription. I guess if they went with the RAM option, and MS did bring in an equivalent feature further down the line (of which I simply don't know whether they will or not!) the customer would be in a great position of having the choice of either.
I think Microsoft accept that there will be customers out there who would like a similar capability in Hyper-V, however in terms of must-haves in R2, I think it fell behind some key features like Live Migration for example.
Who knows what the future will hold - they sure don't tell me what's coming! :-)
Matt
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