I checked my bcdedit /v and there are a lot of file= entries (and they work), so I can’t confirm that there should be only one. In fact, Windows when installed on a vhd creates a file= entry by default. That’s why I tried that also for differencing entries, but that didn’t work, they needed vhd=
To better understand what the differencing and merge process do I made a small test scenario:
01 03 06
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Base.vhd | 02 Word |
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Diff1.vhd | 04 Excel |
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Diff2.vhd | 05 Access | | 08 Outlook |
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Diff3.vhd | 07 Powerpoint |
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01 boot DVD, create vhd, install Windows 7 on vhd
02 install Word (to cache office installation files)
03 boot DVD, create 2 differencing vhd’s and 2 additional boot entries
04 boot Diff1, install Excel
05 boot Diff2, install Access
06 boot DVD, create 1 differencing vhd pointing to Diff2 and 1 additional boot entry
07 boot Diff3, install Powerpoint
08 boot Diff2, install Outlook
09 boot Diff3, BSOD 0x0000007B (0x80D98A90,0xC000000E,0x00000000,0x00000000)
10 boot DVD, merge Diff1
11 boot Diff2, Login possible, but a few critical services don’t startup
12 boot Diff1, everything okay
13 boot Base, everything okay, Excel is installed so the merge worked
Step 09 seems correct, the parent disk for Diff3 is modified so it doesn’t boot up anymore
Step 11 seems weird: Windows 7 starts and I can login but a few critical services (including network, firewall, etc) don’t startup anymore. I expected a BSOD here also, but it seems that the Diff2 vhd can read about 95% of information of Base.vhd. I tried booting in this instance a few more times with everytime the same result. It boots, but the OS isn’t really usable and/or reliable.
But how does this explain whether or not a parent disk must be ReadOnly? In my test I can (from now on) continue to work in Base or Diff1 (with keeping in mind that you will loose al additional things on Base when you do a merge again from Diff1)
Not 100% sure if the above is correct, if anyone can shine a light on this … please 🙂
