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  1. #16
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    Quote Originally Posted by Infinicore View Post
    Been trying out a VM of XP for the better part of a week now with 4 GB assigned and running on a mechanical drive with the host (W7x64) doing "nuthin." While it is definitely better and more responsive than 2 gigs on a 32-bit system, there is still a noticeable hesitation in the simple tasks like browsing an online photo slideshow (an extra one or two mississippi). When it comes to firing up and running something like PaintShopPro X4 and running through a workflow of images for edit, again it was better than my experience with 2 gigs assigned, but it was still very slow, verging on unusable (at 2 gigs it pretty much was unusable), unless one if very patient.

    To make sure I wasn't imagining things I just opened a VM of W7 on XP Pro host that resides on a SSD...OMG OMG OMG!!! It only has 1.5 gigs assigned but it is flying! Almost no noticeable difference between the VM and the host (running on a mechanical drive).

    Conclusion, 4 gigs instead of 2 helps a little, but for me personally there is only one method I've discovered that gets me over that all important inflection point in a sinusoidal curve of usability for VMs; and not just "over" the inflection point but waaaay up top, very comfortably on the shallow part of the curve.

    I've even been able to add a VM to a smaller media type PC, with no SATA ports available, via a SSD, USB 3 dock and card... essentially a remote external OS...works like a charm!!

    Tons and tons of RAM might help but I'm beginning to think that no matter how much RAM is added, the critical factor is still going to be sustainable disk I/O speed.
    4 GB is not much, considering the requirements you have here. Of course, when you have whatever RAM it may be, but short of your needs, then virtual memory becomes relevant and your disk performance is the key to a smooth experience.

  2. #17
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    How much should I give the VM? XP can't use more than about 3.25 anyway even in VM can it?

    If I have to give the VM more than 4 gigs....that's not working.

  3. #18
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    I was actually agreeing with you, so I think the meaning of my reply was misunderstood.
    The XP host OS won't use more than 4 GB. I think you can allocate more than that for a VM (depends on whether you use VMWare or VirtualPC or something else), but you will know you will be using host virtual memory, so from a practical point of view, allocation more than the physically available RAM will guarantee you that the host will have to use virtual memory.

  4. #19
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    The XP host OS won't use more than 4 GB.

    The host is Windows 7 64-bit with 8 gigs of RAM...XP is the VM with 4 gigs assigned so I don't think that is allocating more than the physically available RAM, though as mentioned XP 32-bit probably does not have the full addressable space available for RAM and is probably...well, just ckecked...says 3.15 gigs total.

    If you got the nature of the host and VM mixed up then that explains the misunderstanding...or else I don't understand what purpose there could be for assigning more RAM to a VM than is physically available.

  5. #20
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    First, my concern has always been the host's memory. With less than enough memory, virtual memory comes to play and unless you have an SSD, you will pay in performance. Of course, if your VM has XP, no point in allocating more than 3 GB or so.

  6. #21
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    No there isn't and I don't see a real need to test a 64-bit VM either, I'm quite confident that 6 or 8 gigs allocated won't outperform a 32-bit VM on a SSD with only 1.5 allocated (won't even come close in fact).

    Of course 64-bit with a large allocation of RAM and SSD residence would be the "bomb" but its nice to know I don't have to go thru the hardship of that kind of conversion (if it was only one system it wouldn't be so bad )...just the SSD gets me ~95% of the way there.

  7. #22
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    No doubt the use of an SSD is a very effective way to boost any computer's performance. In a way, in fact, it's like you are adding more RAM, just in much larger amounts than you usually do .
    Last edited by ruirib; 2011-11-27 at 14:25.

  8. #23
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    That is sort of the way I think of it now. More specifically that a 400MB/s read speed is enough to simulate RAM performance whereas the 60-80 MB/s typical read speed for a mechanical drive is not.

  9. #24
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    Networking options: guest network configuration

    Thank you for all the responses to my initial VM questions. [I have been away, so its taken time not only to get back to you all, but to also resume my VM learning].

    Thanks, Doc Brown, for validating my thinking. For some reason I thought that maybe having the same host and guest was some 'off-the wall' crazy idea I was having!

    I have also read through the rest of the responses - and read up on some links (VHD, hypervisors etc.). Also, the discussion on memory and SSD is interesting - and may prove valuable, if/when I need to revisit it.

    Quote Originally Posted by Infinicore View Post
    Before the initial run of the new (copied) VM, I set the virtual network adapter to host only.
    The VM usually needs to reboot anyway, so its at the moment I take the opportunity to change the computer name of the VM and then switched back to bridged network adapter mode after the restart and let DHCP do its thing.

    So I think that gets around both the potential name and IP conflict as well as not disturbing the underlying virtual network adapter. I didn't even think of how the MAC is handled in such cases.
    I have just bought a new retail copy of Win 7 Home, and decided to install Virtual box in preparation for using it as a guest. I notice in reading on the web that there are various networking options for guest network configuration - NAT, Bridged, Internal, and Host-only.

    I read up on these, (particularly http://www.dedoimedo.com/computers/v...k-sharing.html). To tell the truth I don't much understand much of the discussion which presumably refers to various diverse situations - although the article seems, like infinicore, to recommend/use Bridged networking.

    I gather that the main advantage of a Bridged connection is a direct link between the internet connections for the host and the guest - whereas with NAT the guest is secluded and there is no network sharing with the host; also the IP address for the guest in NAT is not derived from the host.
    - What about the MAC address - is this always derived from the host's network adaptor?
    - What is the advantage of sharing a connection with the host? Does it introduce some flexibility/advantage?

    I would appreciate feedback on which network approach to use for my situation, and any advantages/disadvantages - particularly any licencing/windows activation complications which I gather occur with MAC address changes.

    Essentially, I have a stand-alone computer system (in post 1, I covered the configuration); my host is Dell OEM Windows 7 Home x64; my guest will be Windows 7 Home x64 retail. I only intend having one computer (and will only shift the guest VHD to another new computer, probably when I replace this one, at some future indefinite date). Also, I will only be using one VM (or clone) at any one time. I have a DSL connection with British Telecom through a hub device called BT Home Hub 2.0 Media Gateway, and the IP address changes if I switch off and switch on the connection (I am able to access the hub device with a password, so I assume it is some sort of router?). The network adaptor on the host machine is Broadcom NetLink (TM) Gigabit Ethernet.

    Infinicore, if you are still there: could you explain why you start with host networking, then change the computer name (to what, from what?), and then switch to Bridged networking.

    Sorry, if the questions are somewhat basic, but I have very little knowledge about networking - although I do know what an IP address and a MAC address is.

    Thanks again.
    Last edited by discs; 2011-11-30 at 19:23.

  10. #25
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    start with host networking, then change the computer name (to what, from what?), and then switch to Bridged networking.
    This seems not to apply to your situation but I'll explain anyway. Its because I am copying an already established VM from another system. That copied VM will still have the bridged network setting and computer name from that system so if I just started it up I would get I.P. conflicts on the network and one or the other would not work on the network at the same time.

    So before I run it the first time I set the adapter to host so it won't even try to get on the network, then when its running for the first time I change the computer name so it is not duplicated on the network, then when I reboot, it has a new and unique name on the network and when I change the virtual adapter back to bridged, it seeks a new and unique local I.P. address and everything is good to go.

    Like I said, don't know what happens to the MAC address but I haven't had any problems with this technique.

    Since you only have one system and you are going to be installing a VM, not copying it, you shouldn't have to worry about any of that stuff. Also the reason to use bridged in the first place is to allow the VM to act like an independent PC wtih Internet and network access. Host only would be for security and "test bed" only type actions.

  11. #26
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    Re: the MAC address.

    A MAC address is the hardware address of the network interface. In standard network interfaces it is programmed into the firmware. In VirtualBox (which I think is what Infinicore uses), it is assigned a random value upon creation of the VM. See chapter 8 of the VirtualBox manual for extra detail.

    So, for all practical purposes it is a single MAC address regardless if you run a single instance or if you implement Infinicore's rather ingenious method for making it "portable".

  12. #27
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    Thanks, infinicore and tinto tech. I understand the ideas you have covered - and they help me, as I go along, further understand the VM context.

    Finally still, has someone got ideas on NAT vs bridged networking? Thank you.

  13. #28
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    In VirtualBox, NAT networking is the default, but I tend to switch it to Bridged.

    The VirtualBox Manual has more detail on the subject, but I'll try to summarise: NAT networking implements virtual router inside VirtuaBox, while Bridged connects the VM to your pre-existing network and obtains a network address from the DHCP Server in your hardware (ADSL/cable) modem router.

    NAT networking in VirtualBox allows you to create IP addresses on an internal network via a Virtual DHCP server. In Bridged, the VM becomes part of your LAN.

    VirtualBox say that NAT is the easiest, and probably it is - if only because one doesn't need to change the setting. However, I've encountered hiccups when I triy trying to share data between a VM and a Host or a between VM's if I run NAT. By switching to Bridged, everything is on the same physical network and I've observed that moving data around is more reliable.

    NAT may be more appropriate in a segregated network where you may wish to isolate various network devices anyway, but for a straightforward host-guest system, I would plump for Bridged.

  14. #29
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    Tinto Tech, your summary is excellent, and clarifies the main differences between NAT and Bridged; one could say then that NAT applies a virtual networking environment, while Bridged uses the hosts real physical network.

    Your points of clarification have enabled me to make a decision to use a bridged configuration. Thank you.

    P.S. I looked to see if this thread can be marked as solved (since if I come across further issues it would be best to raise a specific new thread); but I don't see an option for 'solved'; perhaps someone authorised to do so could please mark the thread 'solved'. Thanks.
    Last edited by discs; 2011-12-01 at 11:03.

  15. #30
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    I wonder are those issues CPU based ?

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