4. května 2012 10:59
I have a application from "manhattan" that uses a license key for activation, this is keyed to the computers MAC address, Bios serial number and computer name, thus when these change I have to contact the vendor for a new key.
My questions are:
1. when a vm is rebooted will the mac or bios serial number change ?
2. when a vm is moved to another host will the mac or bios serial number change ?
Thanks for any answers.
4. května 2012 11:48
the mac is initially assigned dynamically when you create the nic, its supposed to stay the same upon reboot/when you move the vm. however, if you want to, you can also assign a static mac address for your nic in the vm.
the bios serial i am not really sure, it might change with service packs/updates. maybe you can test a vm with sp0 and sp1 with the help of http://blogs.technet.com/b/tonyso/archive/2009/08/20/hyper-v-how-to-detect-if-you-are-inside-a-vm.aspx
4. května 2012 14:04
Every Hyper-V host has its own range of MAC addresses it assigns dynamically. You should configure your VM with a static MAC address to ensure that it won't change.
- Označen jako odpověď Vincent HuModerator 7. května 2012 6:03
4. května 2012 15:31while it is true that every host has its own range, the mac stays the same once applied to the vm. if you live migrate a vm within a cluster, the mac does not change. it also stays the same if you export a vm from a host and import it e.g. in a cluster. it would change if you delete the nic in the vm and add a new one.
4. května 2012 15:42
I've experienced the opposite a number of times. It takes a while, but eventually the MAC will change. I haven't taken the time to figure out exactly what causes it, but it kind of acts like it's got its MAC with a lease time. This caused serious problems back when I started testing linux VM's. I also encountered licensed application failure due to dynamic MAC being changed all of a sudden. Setting a static MAC prevents this.
I'm not trying to start a debate, I'm just saying....
- Upravený Mike_Andrews 4. května 2012 15:43
4. května 2012 16:09wasnt ment as a debate from my side as well, was just my experience. it's a good thing to get more then one view, Ill concur then to better use a static mac
4. května 2012 16:18
and I would have lost if I had wanted to debate as well ;)
while I did not see a mac change when I exported and imported, the dynamic mac addresses do change indeed
7. května 2012 6:23
I'm glad we got that sorted then :-), and thank your finding Ben's article that specifies the possible causes that enforces MAC changes. I seem to have missed that one.
Regarding the BIOS serial number, I can't seem to find any documentation that clarifies whether this is a static value or not. Apparently, the BIOS GUID and serial number are randomly generated when the VM is created, and are set in the VM's XML configuration file.
If I could speculate, I would only assume that this is a static value. A serial number is after all globally used to identify a unique piece of equipment. If this was allowed to change all of a sudden, well that would just be.... stupid.
So to give some potentially useful guidance to the OP: The MAC can be set to a static value and the BIOS serial number (being a serial number) should logically not be allowed to change, but for absolute confirmation we ought to wait for a MSFT response to this.
- Upravený Mike_Andrews 7. května 2012 9:37
21. května 2012 23:56Vlastník
Jumping in late here. As is discussed on my blog post there are a couple of situations where a dynamic mac address for an existing virtual machine will be changed by Hyper-V.
In regards to BIOS GUID / Chassis ID / etc... These IDs never change (ever). But as a result of this it is relatively easy to get virtual machines with duplicate BIOS GUIDs. For example - if you export a virtual machine and then import it multiple times, each virtual machine that you create will (permanently) have the same BIOS GUID.
Specifying that you are "copying" during import does not affect this either - as then we only regenerate the virtual machine ID that is used by Hyper-V, but not the BIOS GUIDs.
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10. prosince 2012 21:49
Is there any method I can use to modify the duplicate bios guid setting I have ?
Any help along this line would be most appreciated.
I have a dozen or so hyperv guest with the same pattern as below.
wmic:root\cli>/node:xxx01 path win32_bios get serialnumber
wmic:root\cli>/node:xxx01 path win32_baseboard get serialnumber
wmic:root\cli>/node:xxx01 path win32_systemenclosure get serialnumber
wmic:root\cli>/node:xxx01 path win32_systemenclosure get smbiosassettag