In Win PE I am trying to restore an image of the system drive (C.  The image to restore is on a portable USB HDD, which is attached and identified as drive I:.  MR Defaults are taken (restore entire C: drive from the image on I.  At last moment before committing the restore MR warns me that 3 partitions will be overwritten.  Two of these are to be expected -- they are on the SSD containing the C: drive (System Reserved and System).  But the third partition listed is the I: drive.  In other words *Macrium Reflect is warning me that the drive containing my backup images will be overwritten!*  That is most certainly not acceptable.  Perhaps this is just a bug in the graphic interface, but I do not dare continue until I know for certain that the restore operation will not try to write anything to the disk containing the source image to be restored.  I can find no mention of anything like this in MR online documentation which seems to address only a trivially simple case..
 Please advise.
  Additional information: The system drive backup that I want to restore was taken under Win 8.1 just before upgrading to Win10.  I now want to restore the backup to go back to Win 8.1.

The default layout for UEFI-based system drives as shown in this MS Technet article includes at least three partitions and sometimes more.  If you backed up the entire drive on which Win 8.1 was installed, the backup image would include a Microsoft System Reserved (MSR) partition and an EFI System Partition (ESP) along with the OS partition ("C:").  Normally, all three of them would also be included in a complete recovery operation and will overwrite whatever is currently on the chosen target drive.

That accounts for the number of partitions to be restored, but not for Reflect's telling you that it's going to overwrite the source partition (assigned "I:" in the rescue environment) on which the backup image resides.  In fact, that would be an impossibility.  Are you sure that you selected the correct drive (i.e., the one on which Win 10 is currently installed) as the target for restoring the Win 8.1 backup image?  Assigning your own volume labels is more reliable than changeable so-called "drive letter" assignments and volume labels can be assigned to partitions that have no "drive letter" at all.


Regards, Richard V. ("Arvy")

Arvy,
Thank you for responding.
The MS document you referred to was for Windows 7.  The machine I am working on was born with Windows 8 (original OEM install) and later upgraded to 8.1.
I have taken 5 photographs which show the partition setup, the MR dialog and the final warning about overwriting (at that point I cancelled rather than continued).
Here is the partition setup (seen in Win 10 but I am certain it was the same in 8.1).

Here is the Macrium Reflect setup:

Note that the file to restore (the source file) is prefaced with drive name I:
After clicking "Restore Image" we get:

Note above that drive H: (450MB) has now turned up as part of the destination.

This summary (above) looks OK, but:

I took the warning above literally, believing drive I: to be the drive with the source file, and therefore cancelled out.  However I am now realizing that what has become drive I: is probably not the 466GB source file drive, but rather the 450MB recovery partition seen in the first photo and later seen as drive H: in MR. The inconsistent shuffle of drive letters is what has caused the confusion.
Do you concur with that?  Do you see anything else that should concern me before restoring the Win 8.1 backup image?
Thanks for your assistance.
Bob

Microsoft's recommendations on system drive "geometry" haven't really changed from Win7 to Win10 other than the addition of a Window Recovery (WinRE) partition for each upgrade.  The more recent Win 10 partition layout details, if you want to look them over, are shown for UEFI-GPT setups in this MSDN article and for BIOS-MBR setups in this MSDN article.  It appears that your system drive (Disk 1 in your Windows Disk Management screenshot) is the latter.  It still shows three partitions if the recovery partition is included, but there is no "I:" partition on that recovery target drive at all.

The recovery source backup image, on the other hand, includes only two partitions: the System Reserved partition and the OS partition.  Only those two are needed for a bootable BIOS-MBR result.  Replacing the existing WinRE partition ("H:") on the target drive is not actually essential for your Win8.1 rollback recovery purposes and it can safely be ignored.  There is no "I:" partition that is required to be involved at all, neither in the source image nor on the target drive.

To keep things as simple as possible in the circumstances, you only need to drag and drop the System Reserved partition (no "drive letter") from the backup image onto System Reserved partition ("E:") of the target drive and the OS ("C:") partition from the backup image onto the OS ("C:") partition of the target drive.  The latter will need to be shrunk slightly because of the added WinRE partition ("H:") on the target drive, but that's not an immediate issue of any real consequence.  More details in this KB article if wanted.

Having restored those two partitions and while still in the WinPE rescue environment, you may also need to run Reflect's "Fix Windows Boot Problems" to get the system booting normally to Win 8.1 again.  Once back in the regular Win 8.1 working environment, you can use Windows Disk Management to extend the OS ("C:") partition after first removing that additional WinRE partition using DISKPART if it's unneeded and unwanted.  In any case, it's harmless.


Regards, Richard V. ("Arvy")

Arvy,
I ran the restore and everything seems to be OK under Win 8.1 again.
Win 10 was all mischief and no reward for this desktop workstation user.  All the new "features" were for toys, not workstations, and incompatibilities (not mentioned by MS) kept creeping out.  Little things, mostly, but aggravating anyway.  The breaking point came when I realized that the upgrade seemed to have bypassed the Intel RST support for my 4GB mirrored D: drive, causing almost endless churning as the RAID driver struggled to re-sync the drives after each write.  That's my analysis, anyway, based on the symptoms.  No help from Intel, of course.  So far, under 8.1 the drives are quiet again, just as they used to be before Win 10.
Based on what I had already seen, I didn't like the idea that MS might also "update" me with more mischief without warning at any time.  So I intend to stay on 8.1 doctored with Start8 and a few other circumventions of the garish toy tile interface.
Anyway, thanks for your help with the restore.    
Bob (cognitive93)

You're welcome, Bob.  Glad to hear it all worked out okay for you.  The Windows 10 story and its recent "Anniverary Update" could be an almost endless and controversial discussion, so I'll simply say that I don't disagree with what you've said.  My own way of dealing with the issue has been to keep W10 in what I call "experimental mode" with plenty of reversion backups and I can multi-boot my system to any one of three Windows installations: 7, 8.1 or 10.  That way, I get to play with all Microsoft's so-called "upgrades" without the risk.  Very fortunately, Reflect is licensed on a "per machine" basis so I can run one license under all Windows versions on the same machine -- plus WinPE bootables, of course. :^)

__
P.S.:  I also have Linux Mint installed and running everything except a few apps I haven't found replacements for yet -- if that tells you anything.


Regards, Richard V. ("Arvy")