Hi @renarde

The limit is the maximum size of the file system being imaged, and for NTFS that's 8 Petabytes.

Macrium Reflect has no limit or restriction on the image file size. Any limit is imposed by the file system that the image is stored on.

Kind Regards

Joe A

Macrium Support Team

See our reviews on

@jphughan, thanks for continuing to assist and for those insights! That's *very* helpful, and gives me a place to start checking. We'll look into the mergerfs and user configurations on the NAS and see if there are any user limits that are causing problems.
In the meantime, to simulate the Reflect job I started a manual copy of all the data on the large Windows drive to the backup drive. I'm curious to see if it will also fail.
Since you've been in Windows IT for 15 years you've seen your share of WinOSes. I must admit - my favorite is still XP. It's more transparent to power users with a lot less clutter and obfuscation

Happy to help!  I had a soft spot in my heart for XP for a long time, but when I came back to it after having used Windows 7 for several years, it felt a little too much like stepping back into the Stone Age for my liking, and the default Fisher Price interface that seemed so shiny when it launched just looked goofy in hindsight.  And my IT side also biased me against that OS compared to its successors because as annoying as people found UAC to be when it was first introduced, it was responsible for something like a 90% reduction in successful malware attacks (this was of course before ransomware).  Turns out that having everybody run with full admin privileges all the time, without even requiring reauthentication for elevated operations, was a horrible idea from a security standpoint -- which had been obvious in the Linux and Mac world for quite a long time.  (That's why I thought the "I'm a Mac, I'm a PC" commercial that made fun of UAC was unfair, since Mac OS prompted for reauthentication during elevated operations too, which I regarded as a good thing.)  But when you're the de facto tech support person for all of your family, friends, and neighbors -- on top of the people you're paid to take care of full-time -- OSes that allow users to get themselves into a bunch of trouble and create a bunch of work for you don't tend to remain in your favor for very long after there are better solutions available.

And as much as Windows 10 annoyed me for quite a while, now when I step back into Windows 7, there are too many features I've come to like and rely upon in Windows 10 to make me just as happy on Windows 7.  That's especially true in the PowerShell world, where MANY useful cmdlets have been introduced in versions since Windows 7.

True, UAC is very helpful for for preventing malware infections and keeping people from massively screwing up their Windows installs. Comes in handy and when you're tech support for family and friends
I'll have to give PowerShell another try and see how it can make my life easier on my Win 10 machines

My manual copy revealed that I had a handful of files (sent to my by friends) that had names so long that the storage drive generated error messages about their length. Otherwise, the copy completed successfully, so I don't think the backup was failing because of limits on the amount of space a user can use on the Linux backup volume.

If the regularly scheduled backup succeeds tonight then I'll know the problem was the excessively long file names. I'll keep you posted!

@JoeA thanks for your quick response and letting me know that Reflect doesn't have any backup file size limitations. And no offense, but if I get close to 8 Petabytes of data I'll be using something other than Reflect to back it up! Right now I've got about 35Tb of data and that's plenty.

@jphughan my regularly scheduled backup failed, so apparently I either missed a problem file or a long file name wasn't the issue.

We checked the user definitions on the backup drive and there were no size limits set. Just to confirm that's true I hand copied all of the uncompressed data on the drive I'm trying to back up to the backup volume, and was able to copy two full sets of data. Having done so, the available drive space on the 10.7Tb backup drive has dropped to 1.27Tb, over a terabyte less than when the backup jobs that I've been asking about were failing. In spite of that, other automated Reflect backups to the same backup drive have been completing successfully, including ones that ran early this morning and backed up data from the same drive. In short, user data limitations on the backup drive don't appear to be the problem. It appears to be something about the way the problem backup is configured, or what it's trying to copy.

So I determined how large each directory is, and created two new File and Folder backup definitions. Each contains roughly half the data on the drive, and both ran successfully overnight. While it's not the solution I was hoping for it seems to be working.

Thanks again for your help, and I hope you have a healthy, prosperous, happy 2023

Hey @renarde, thanks for circling back with an update! Glad to hear you’ve got a solution that works, but it’s still strange that the original job didn’t work, since it sounds like it should have. If you’re so inclined, you might consider opening a formal support ticket with Macrium about this so they can work with you to gather more information about what’s going on. Macrium’s engineers are very good, so the most likely outcomes are that you’ll a) clearly understand why your original setup isn’t feasible (least likely in my opinion), or b) you’ll know what had to be tweaked to make it work, or c) you might uncover a Reflect bug that Macrium will then be able to issue an update to resolve. So whatever the outcome, I think there’s very likely value to be gained by sticking with this a bit. But I also understand that everyone’s time is finite, so if you’re happy with the setup you’ve got now and want to move on with life, that makes perfect sense too

Hi @jphughan, thanks again for your good suggestions. I did indeed open a support ticket on the 4th, and JoeA from Macrium responded saying he'd work with me through this forum. He's the one who pointed us at a filesystem/user configuration issue. My (very amateur) testing doesn't seem to support that conclusion.

I'm a firm believer in making sure I post solutions in my support threads to help others who run into similar issues, so I'm good with continuing to research this. If I bump my support ticket do you think someone at Macrium will help me dig into this further?

So did you ever get this fixed? I've had the same issue for a while now. It's ridiculous because it makes the app pointless.

I have never heard of backing up that much data all at one time.

If 70% of it remains the same, then move it to another drive and use something like syncback on individual folders.

Leave main drive free for operating system and a few other key programs, i.e., office apps, etc.

For example I have 2 drives, one I code jakarta ee on, and use Freecad and python, and store images, that's D: drive.
On C: drive I have operating system and some key programs like Office and Mcafee antivirus installed.

I use macrium on the disk with the c: drive.  I use syncback with D: drive, but only sync the folder I know I currently wrote to or changed a file.
Of course all is still backed up to an external USB drive.

Just a suggestion, but I would consider thinking about doing it this way.  I would not want to ever backup even one TB all at one time. Syncback has a free version which works great and you can write backup scripts as well.