I use Macrium for partition images and whole disc image backups which go via USB to my external HDD.
Never failed with my 7 year old 32 bit XP Laptop and Comodo 3.14.
I now have a much more recent high powered 64 bit Desktop with a clean install of Windows 7 Ultimate, using Comodo 5.3.176757.1236.
A Macrium Boot CD created on the external drive a 6 GB image of the Desktop primary MBR HDD,
and this validated perfectly.
Because it was a Boot CD there could be no corruption by Comodo.
Macrium has created on the secondary internal GPT drive 4 off 6 GB images plus 4 off 1 GB Differential images, all perfectly validated.
For extra security I selected all 8 images and duplicated this group on the external drive, using the normal Windows drag/drop copy procedure.
The smaller differential images were lucky, their duplicates validated.
Only 1 of the 6 GB images was lucky, the other 3 failed to validate.
MD5 checksums confirmed the 3 failures were different from the originals,
and repeating the checksums got the same consistent answers - errors on what had been written.
My experience with Comodo 3.14 was that when copying or scanning a larger group of files,
everything was much faster and smother if I disabled A.V. and Defense+ (and of course blocked the Internet).
Therefore I set Comodo 5.3 to block the internet and disable A.V. and Defense+,
and then I successfully duplicated the images which were validated.
SUMMARY :-
Comodo Active - 3 failures out of 4 attempts
Comodo Passive - 3 successes out of 3 attempts.
Those statistics indicate a fair chance that Comodo is implicated in a data corruption of 1 bit in 6,0000,000,000 * 8
either because Comodo did damage, or because it was consuming precious processor cycles with concerns about the safety of the files that Windows was copying,
or perhaps Defense+ has never seen a file being copied from a GPT dynamic disc via USB2 onto an external MBR disc.
I suspect that Comodo may not ignore the 6 GB files, but detect that they contain millions of compressed files,
hence lots of inspection.
Should I tell the A.V. to ignore the Macrium image file extension which is “MRIMG” ?
By default the A.V. has “exclusions” which include “C:\Program Files\COMODO\COMODO Internet Security*”
Can I add to the list “*.MRIMG”
Or do I have to also stipulate the Drive and Path of the original and or the intended duplicate ?
Is there some adjustment to Defense+ that would reduce its concerns about copying from GPT to MBR ?
Any advice will be appreciated.
N.B. For many years I was happy with FAT32,
and regret my loss of control under NTFS where permissions always strike at the worst possibles times.
I know very little about GPT and that make me nervous ! !
Regards
Alan