kellyapproved@xxxxxx wrote:
Quote:
> When you setup a guest OS, you need to allocate RAM to it.
>
> Let's say you have a host with 3 GB of RAM with two guests, each of
> which you allocate 1 GB of RAM.
>
> If both guests are in use, the host and two guests will get 1 GB of
> RAM each.
>
> Is there a way to set it so that if only 1 guest is in use, it can
> draw on the spare RAM that is allocated to the other guest that is not
> used.
Unfortunately not. Remember that to the operating system inside the
Guest PC, the virtual PC is a real PC and the amount of memory in a real
PC typically cannot change without a reboot.
Currently I don't think the following facilities exist in MS VPC, but
they would be nice to have for your (common) problem:
1. Allow the virtual RAM given to a virtual PC to come from the Host PCs
virtual memory, not physical memory (in other words allow it to be
swapped out to the regular pagefile.sys of the host OS, just like
ordinary application memory consumption). This would allow running more
and larger virtual PCs on the same hardware, at the cost of some of
those virtual PCs running slower.
2. Adapt the amount of virtual RAM given to a virtual PC at virtual PC
reboot to depend on available real RAM at that time.
3. In the Virtual PC extensions for various operating systems, include
code that releases unused RAM pages back to the Host PC, thus making the
memory requirement smaller when the Guest OS is idle.
4. Emulate the advanced support for physically adding and removing
hardware memory without a reboot as found in expensive high end servers.
Many recent operating systems such as Server 2008 (and thus in
principle Vista too) contain support for handling hot memory
plugging/unplugging and could thus be made to cooperate with a variable
RAM size Virtual PC.
For Microsoft's own operating systems they could make a license
exception allowing the hot plug support to be used in Virtual PC (or
equivalent) Guest environments, even in SKUs that are not otherwise
licensed to include support for such high end servers.
--
Jakob Bøhm, M.Sc.Eng. * jb@xxxxxx * direct tel:+45-45-90-25-33
Netop Solutions A/S * Bregnerodvej 127 * DK-3460 Birkerod * DENMARK
http://www.netop.com * tel:+45-45-90-25-25 * fax:+45-45-90-25-26
Information in this mail is hasty, not binding and may not be right.
Information in this posting may not be the official position of Netop
Solutions A/S, only the personal opinions of the author.