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Shadow copying

wlie :

Oct 03, 2013

I have just installed and tested ver. 37.  Everything works without problems.
I am especially fond of the feature that makes the destination to be recognized (fingerprint). However, one must not format the destination between two jobs, then there is no recognition (it was stupid of me).

Question:
I think I understand what Shadow Copying means, but why there are four options are unclear to me.
"Do not use" is OK, either you want it or you don't.
"Use if needed"?
"Use if available"?
"Require"?
Perhaps the answer is in the forum, but I'm too lazy to review them all.
William

Alex Pankratov :

Oct 03, 2013

However, one must not format the destination between two jobs, then there is no recognition (it was stupid of me).


This is controlled with "Detecting changes" preference in the backup config. If you set it to "re-scan", it will catch this sort of situations and re-copy what's missing.

Alternatively, you can click Go while holding Control down and it will too cause destination re-scan.

"Use if needed"?

The app will switch to VSS only if it runs into a locked file

"Use if available"?

If the app can make a VSS snapshot at the beginning of a backup, it will do that. If not, it will still proceed.

"Require"

Same as preceding item, but it will fail backup if VSS is not available.

Alex Pankratov :

Oct 03, 2013

.
Added this to the context help thingy - http://bvckup2.com/wip/shadow-copying-hint.png
This will be in the next release (BR38).

mikeyww :

Dec 03, 2019

v80.7: Shadow copying not available.... though Robocopy succeeds with the same folder that fails in Bvckup.

mikeyww :

Dec 03, 2019

Re: the shadow copying: it's a folder on an encrypted volume.

Alex Pankratov :

Dec 03, 2019



Robocopy doesn't use shadow copying. You can mimic it in bvckup2 by setting "Shadow Copying" to "Don't use" in "Backup Settings" > "More Options".

Don't know what you use for your volume encryption, but shadow copying is not in fact supported by True/VeraCrypt due to Microsoft's restrictive licensing of the VSS SDK.

mikeyww :

Dec 03, 2019

OK. I use Cryptic Disk. In any case, I created a workaround by using RawCopy for the locked file.

https://github.com/jschicht/RawCopy

Thank you.

Alex Pankratov :

Dec 04, 2019



Careful with that. While it _will_ copy a locked file, there's a substantial risk it will copy it in an inconsistent state, rendering it unusable afterwards.

Also I didn't quite understand you first time around. If robocopy can copy files and bvckup2 runs into an error, you should be able to fix this by changing the sharing mode in which bvckup2 accesses source files. For a number of reasons it defaults to both ShareRead and ShareWrite, but changing this just ShareRead may solve your issue. If you want to try this, let me know and I'll explain the details.

* This will however come with the same caveats as the RawCopy option.

mikeyww :

Dec 04, 2019

Thank you for the information; I was unaware of this. When I ran Robocopy again, it did fail and reported a sharing (file lock) error. Nonetheless, it seems like I should try your ShareRead-only solution. If it works, then it sounds like it would be at least as good as RawCopy.

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