Dual boot after final release

dencal said:

Just chipping in with my own experience of dual booting W8.1 and W10 Preview latest two versions on two separate SSD,s both connected in the computer.

Each update messed up the MBR on both systems.

Have overcome the problem by hot swopping, one in one out.

Yeah, I'm working up a procedure to grow the System Reserve partition on MBR initialized disks from what Win7 and Win8.1 create when they are installed 100 MB (steal 350 MB from C:, move C: to the right, then add the 350 MB to SysReserve = 450 MB).

It's fairly easy to do, not so easy to document

I had issues and a few other members got past install issues by doing this.

My 450 MB System Reserve only has 28% free space now - the contents are definitely larger than 100 MB

The size returned by dir /a /s doesn't match the above usage. There's a Recovery and the the System Volume Information folders that don't seem to be included in the dir count though

Total Files Listed:
93 File(s) 19,064,138 bytes
137 Dir(s) 133,562,368 bytes free

GPT initialized disks are not affected, one member reported that a new 450 MB System Reserve was created to the right of their C: drive. I suppose MS determined it was too difficult to affect MBR disks at install time due to the 4 partition limitation - most OEMs use all four (System Reserve, Windows, Recovery, Utility???).

The Technet MBR disk schema recommends 350 MB for a combined System Reserved / Recovery partition, so I just used that as a base and added 100 MB for good measure.

I just got this back from Microsoft Insider: (Interesting that you can type with an accent.)

4kays,
There seems to be not clear somewhere.
How did you install Windows 10, wiht dual-booting Windows 7 SP1 (laptop dual-booting?) and Windows 8.1 (Desktop dual-booting ?)?
If you have Windows 10 both clean installed on your machines, then you will get newer builds only if you stay as the Insider, for free. Otherwise, you could just get the free from upgrading Windows 7 SP1 or Windows 8.1.
If your current Windows 10 is upgraded from an earlier operating system (not include Enterprise), then there is not so much aspects to worry about.
We may make bootable media for recovery after the official release of Windows 10.
Then clean install would be OK on your verified machines, with your registered Microsoft Account.
Any further concerns, please feel free to post back.
Regards