> On Wed, 14 Jan 2009 11:58:42 -0800, news.microsoft.com wrote:
>
>> I was told that it was best practices to let the host system manage the
>> swap
>> file, however I have noticed that when I hit the physical memory limit I
>> can
>> no longer start virtual machines. I was under the impression that server
>> 2008 fixed the issue of hitting the hard limit on physical ram by
>> swapping a
>> portion of it. Am I totally wrong here? If not, what would be the point
>> to
>> let the host manage the swap if it does not swap to begin with?
>
> Using a pagefile for virtual memory management and over-committing memory
> for virtual machines are two completely different things. No Microsoft
> virtualization solution allows you to over-commit memory.
>
> --
> Paul Adare
> MVP - Identity Lifecycle Manager
> http://www.identit.ca

> I was told that it was best practices to let the host system manage the swap
> file, however I have noticed that when I hit the physical memory limit I can
> no longer start virtual machines. I was under the impression that server
> 2008 fixed the issue of hitting the hard limit on physical ram by swapping a
> portion of it. Am I totally wrong here? If not, what would be the point to
> let the host manage the swap if it does not swap to begin with?

> Well, coming from a VM world, I had the ability to allocate directly to
> phsyical RAM or the option to allow some of the RAM for the VM Machines to
> leak into the pagefile. Did I loose this functionality in Hyper-V?

> On Wed, 14 Jan 2009 14:31:55 -0800, news.microsoft.com wrote:
>
>> Well, coming from a VM world, I had the ability to allocate directly to
>> phsyical RAM or the option to allow some of the RAM for the VM Machines
>> to
>> leak into the pagefile. Did I loose this functionality in Hyper-V?
>
> The feature in VM is over-committing memory and yes, Hyper-V does not
> allow
> that.
>
> --
> Paul Adare
> MVP - Identity Lifecycle Manager
> http://www.identit.ca

>So what I gather from all of this
>is that even though microsoft recomends that you do not swap in the guest
>Machines, unless you have the luxury of having enough physical RAM to cover
>spikes, you are better off placing a swap inside the VM's.
>I somewhat disagree, because sometimes you can have a spike of memory usuage
>and if you decide that due to cost swap is the best method for distributing
>this spike I would not call that over commiting, just a backup plan that is
>cheaper/more realistic than physical RAM. So what I gather from all of this
>is that even though microsoft recomends that you do not swap in the guest
>Machines, unless you have the luxury of having enough physical RAM to cover
>spikes, you are better off placing a swap inside the VM's.
>
>
>"Paul Adare" <(email address - cut out)> wrote in message
>news:1fkhrylk7of87$(email address - cut out)...
>> On Wed, 14 Jan 2009 14:31:55 -0800, news.microsoft.com wrote:
>>
>>> Well, coming from a VM world, I had the ability to allocate directly to
>>> phsyical RAM or the option to allow some of the RAM for the VM Machines
>>> to
>>> leak into the pagefile. Did I loose this functionality in Hyper-V?
>>
>> The feature in VM is over-committing memory and yes, Hyper-V does not
>> allow
>> that.
>>
>> --
>> Paul Adare
>> MVP - Identity Lifecycle Manager
>> http://www.identit.ca
>

> >I would not call that over commiting,
>
> That's what it's called though, it's just a term meaning you are
> allocating more memory than you have for a VM and Hyper-V doesn't do
> that.
>
>>So what I gather from all of this
>>is that even though microsoft recomends that you do not swap in the guest
>>Machines, unless you have the luxury of having enough physical RAM to
>>cover
>>spikes, you are better off placing a swap inside the VM's.
>
> Correct. Otherwise it's a very tight balancing act between working
> set and RAM available, most of the time not worth it to do, but if
> performance is the most desired option, not swapping in the VM would
> be the best.
>
> --
> Bob Comer
>
>
>
>
> On Thu, 15 Jan 2009 08:25:31 -0800, "news.microsoft.com"
> <(email address - cut out)> wrote:
>
>>I somewhat disagree, because sometimes you can have a spike of memory
>>usuage
>>and if you decide that due to cost swap is the best method for
>>distributing
>>this spike I would not call that over commiting, just a backup plan that
>>is
>>cheaper/more realistic than physical RAM. So what I gather from all of
>>this
>>is that even though microsoft recomends that you do not swap in the guest
>>Machines, unless you have the luxury of having enough physical RAM to
>>cover
>>spikes, you are better off placing a swap inside the VM's.
>>
>>
>>"Paul Adare" <(email address - cut out)> wrote in message
>>news:1fkhrylk7of87$(email address - cut out)...
>>> On Wed, 14 Jan 2009 14:31:55 -0800, news.microsoft.com wrote:
>>>
>>>> Well, coming from a VM world, I had the ability to allocate directly to
>>>> phsyical RAM or the option to allow some of the RAM for the VM Machines
>>>> to
>>>> leak into the pagefile. Did I loose this functionality in Hyper-V?
>>>
>>> The feature in VM is over-committing memory and yes, Hyper-V does not
>>> allow
>>> that.
>>>
>>> --
>>> Paul Adare
>>> MVP - Identity Lifecycle Manager
>>> http://www.identit.ca
>>

>Yup...Thanks for all the help!
>"Robert Comer" <(email address - cut out)> wrote in message
>news:(email address - cut out)...
>> >I would not call that over commiting,
>>
>> That's what it's called though, it's just a term meaning you are
>> allocating more memory than you have for a VM and Hyper-V doesn't do
>> that.
>>
>>>So what I gather from all of this
>>>is that even though microsoft recomends that you do not swap in the guest
>>>Machines, unless you have the luxury of having enough physical RAM to
>>>cover
>>>spikes, you are better off placing a swap inside the VM's.
>>
>> Correct. Otherwise it's a very tight balancing act between working
>> set and RAM available, most of the time not worth it to do, but if
>> performance is the most desired option, not swapping in the VM would
>> be the best.
>>
>> --
>> Bob Comer
>>
>>
>>
>>
>> On Thu, 15 Jan 2009 08:25:31 -0800, "news.microsoft.com"
>> <(email address - cut out)> wrote:
>>
>>>I somewhat disagree, because sometimes you can have a spike of memory
>>>usuage
>>>and if you decide that due to cost swap is the best method for
>>>distributing
>>>this spike I would not call that over commiting, just a backup plan that
>>>is
>>>cheaper/more realistic than physical RAM. So what I gather from all of
>>>this
>>>is that even though microsoft recomends that you do not swap in the guest
>>>Machines, unless you have the luxury of having enough physical RAM to
>>>cover
>>>spikes, you are better off placing a swap inside the VM's.
>>>
>>>
>>>"Paul Adare" <(email address - cut out)> wrote in message
>>>news:1fkhrylk7of87$(email address - cut out)...
>>>> On Wed, 14 Jan 2009 14:31:55 -0800, news.microsoft.com wrote:
>>>>
>>>>> Well, coming from a VM world, I had the ability to allocate directly to
>>>>> phsyical RAM or the option to allow some of the RAM for the VM Machines
>>>>> to
>>>>> leak into the pagefile. Did I loose this functionality in Hyper-V?
>>>>
>>>> The feature in VM is over-committing memory and yes, Hyper-V does not
>>>> allow
>>>> that.
>>>>
>>>> --
>>>> Paul Adare
>>>> MVP - Identity Lifecycle Manager
>>>> http://www.identit.ca
>>>
>