Windows 10: Backup and compare with robocopy not working

antonio3535 · May 5, 2021

I've backed up the Windows folder from a Windows 10 boot drive with robocopy F:\Windows E:\roboRubi\Windowsz /mir Both source and target drives are attached to internal SATA ports. None of the two drives (source and target) is the boot drive I'm booted into. I'm using an elevated command prompt. I compared the two folders afterwards in File Explorer and found that, surprisingly, the backup folder has more files and overall size than the source folder (as shown in picture). I suspect both folders are really the same, but that Windows 10 may not be accessing all files in the source folder due to permission issues, I mean when I compare then in File Explorer? So I tried to compare both folders with robocopy F:\Windows E:\roboRubi\Windowsz /L /NJH /NJS /NP /NS /log:C:\compare.txt but this doesn't seem to work, it just instantly displays this path and does nothing: Log File : C:\compare.txt Is there a way to check this backup properly? I'd rather use robocopy than any other third party tool. Any help much welcome Windows 10 Pro 20H2.

:)

antonio3535 · May 5, 2021

Backup and compare with robocopy not working

I've backed up the Windows folder from a Windows 10 boot drive with

robocopy F:\Windows E:\roboRubi\Windowsz /mir

Both source and target drives are attached to internal SATA ports. None of the two drives (source and target) is the boot drive I'm booted into. I'm using an elevated command prompt.

I compared the two folders afterwards in File Explorer and found that, surprisingly, the backup folder has more files and overall size than the source folder (as shown in picture).

I suspect both folders are really the same, but that Windows 10 may not be accessing all files in the source folder due to permission issues, I mean when I compare then in File Explorer?

So I tried to compare both folders with

robocopy F:\Windows E:\roboRubi\Windowsz /L /NJH /NJS /NP /NS /log:C:\compare.txt

but this doesn't seem to work, it just instantly displays this path and does nothing:

Log File : C:\compare.txt

Is there a way to check this backup properly?
I'd rather use robocopy than any other third party tool.

Any help much welcome

Windows 10 Pro 20H2.

antonio3535 · May 5, 2021

Backup and compare with robocopy not working

Have not found anything really earthshattering, but from what I do know I would think that the proper way to do this would be something like this:

1) Create a shadow copy of the drive first.
2) Begin your backup of that shadow copy.
3) When done, do your comparison with the shadow copy.

Note that this is the technique used by backup programs such as Macrium Reflect.

The whole point of a shadow copy is that you can backup files that would normally be in use and also so that things are not changing on you while the backup is being performed. Once the shadow copy is created, you have a consistent set of data that will not change until that shadow copy is destroyed.

As an example, I have a drive with an excel spreadsheet. I start a backup that begins with the creation of a shadow copy. In the middle of the backup, a user deletes that spreadsheet and the backup has not yet gotten to the folder where it resides. It doesn't matter because the file is still preserved in the shadow and so it will be backed up.

That's my thinking on the matter, but if anyone has other thoughts, please do say. I'm interested in learning something here *Smile

More info can be found here:

Backup Internals: What is VSS, how does it work and why do we use it? | by Macrium Software | Macrium Software.
Click to expand...

I didn't mention that none of the 2 drives involved (source and target) is the boot drive I'm using, as I thought the E:\ and F:\ paths would be telling (sorry I wasn't more clear).
I'll try again with the /b (both on the backup and on the comparison test) and come back to you.
Thanks a lot for your answers.

- - - Updated - - -

The problem is both permissions and use a lot of files may be locked as they are in use and some may change while windows is running so your never going to get an exact match just copying
Click to expand...

I didn't mention that none of the 2 drives involved (source and target) is the boot drive I'm using, as I thought the E:\ and F:\ paths would be telling (sorry I wasn't more clear).
I'll try again with the /b (both on the backup and on the comparison test) and come back to you.
Thanks a lot for your answer

- - - Updated - - -

Windows' count of the in C:\Windows files while Windows is running & its estimation of their size are known to be useless.
- That's why tools such as Treesize as recommended for people investigating issues within C:\Windows.

So this thread seems to be about comparing the incorrect count of files with another count of files derived from that incorrect count of files.

No correct answer can possibly come from this.

Antonio - If your aim is to get a full copy of the C:\Windows folder then boot from an InstallUSB to do it. You can still use RoboCopy.
- Size comparisons might still be rubbish. C:\Windows includes some items [such as many within the component store] that appear to be files but are really hard-wired redirections to files that are elsewhere within C:\Windows. I have no idea how RoboCopy will cope with them.
- I think you'd be better off making a system image.

Denis
Click to expand...

I tried with Treesize and it gives me exactly the same result as File Explorer. Then I compared source and backup with WinMerge and the result seems to indicate that neither File Explorer nor Winmerge are accessing some files and folders in the source directory.

My initial question is partly solved by adding /B to the robocopy comparison command:
robocopy F:\Windows E:\roboRubi\Windowsz /L /NJH /NJS /NP /NS /B /log:C:\compare.txt
...but I don't understand the output file, it seems to show all of the file transfers instead of only the differences? what I need is the differences.

hsehestedt · May 5, 2021

Backup and compare with robocopy not working

You forgot to add the /NDL switch I noted previously. Without it, robocopy will list every blasted directory whether there are any differences or not. Add the /NDL and only file differences will be shown. Note that the full path for each file will still be shown. Also, missing and extra directories will still be shown. The /NDL will merely suppress the listing of every directory that is not relevant to actual differences.

Windows 10: Backup and compare with robocopy not working

Backup and compare with robocopy not working

Backup and compare with robocopy not working

Backup and compare with robocopy not working

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