Backup Kept Running When Disk Was Removed

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thesmall
Posts: 2
Joined: 06 Feb 2023, 16:36

Backup Kept Running When Disk Was Removed

Post by thesmall »

Pre-Issue Stuff:

Long-time user of Gravity and now Reflector. Thank you for all of the work and effort you've put into this product.

I didn't see any forum posts about this particular issue. I imagine this problem is something that doesn't happen that frequently. If there is a forum post about this issue, apologies, and please feel free to point me there.

Information:

Windows:
Edition Windows 10 Pro
Version 22H2
Installed on ‎1/‎24/‎2021
OS build 19045.2486
Experience Windows Feature Experience Pack 120.2212.4190.0

Cobian Reflector:
v2.3.5

Source Disk:
3x 4TB Western Digital Red, RAID 5, using Windows Storage Spaces

Destination Disk:
Western Digital My Book 25EE 8TB

Job Information:
Mirror 5x source directories to a destination directory. No compression or anything else fancy. Straight copy.

Problem Statement:

1. During the execution of a backup, the source (virtual) disk serving the data that was in the process of being backed up, went offline. Why the disk went offline remains to be seen, though I have some suspicions - almost certainly not related to Cobian Reflector.
2. When the disk went offline, the existing files that were queued up failed to backup, naturally.
3. After this though, the next set of sources due to be backed up could also not be found.
4. Because the sources could not be found, and because Mirror task flag was checked, those sources were wholly deleted.

Thoughts:

This behavior seems problematic.
It's one thing for the disk to be connected and the folders no longer existing, causing the non-existent folders to mirror to the destination. The Mirror task would have done exactly what it was supposed to do.
It's another thing entirely for the whole volume to be have gone offline/be missing, and the lack of volume cause the "empty" source directories to mirror to the destination.

The failure mode when an entire volume goes offline should probably be for the task to critically fail and stop, rather than continuing on.

Fortunately, the virtual disk came back online in Windows (manually, by me)... seemingly without issue or data loss (though this is not an easy thing to confirm). I have removed the possibly-offending software (Corsair iCue) I think caused the issue, and I am running another backup to get back to a state where the things I want protected are in fact protected.

I can provide the log file upon request, if there is a way to communicate it securely. I am not keen to just upload it to a public forum, even though I've done my best to sanitize it. This can be a secure repository of your choosing, or I can share a google Drive link via Direct Message.

Questions:
1. Would the setting "Cancel if Volume Shadow Copy fails" have properly handled this issue?
2. Is there some other setting I should have enabled to mitigate this issue?
3. If this is a bug or functional oversight, is there a place to submit bug/feature requests outside of the forum?


Thank you.
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cobian
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Re: Backup Kept Running When Disk Was Removed

Post by cobian »

Yes, this is the danger with Mirrors and that's why it's important with the Safe Mirror Directory. Some other problem is: IF some virus or hard drive problem makes some files in the source unavailable, the backup of those files will be deleted as well. A mirror is NOT a backup. To somehow mitigate this problem, the files are deleted to the Safe mirror directory.
--
Luis Cobian
Cobian Backup's creator
thesmall
Posts: 2
Joined: 06 Feb 2023, 16:36

Re: Backup Kept Running When Disk Was Removed

Post by thesmall »

Thank you for getting back to me.

I recognize the danger of using the mirror option, but it's been preferable to me rather than inadvertently restoring a bunch of data that I purposefully deleted/renamed months and years ago. Perhaps you (or anyone else reading along) have a recommendation one how I can mitigate this behavior.

The dataset in question is too big to have safe-mirrored during the backup process. It basically requires double the space of the source data to safely mirror all of the content. As much as I would like to, I cannot currently pull that off.

I will consider turning off the mirror option, and contending with the annoying behavior I mentioned earlier, but I do wonder if it would be possible suggest a feature request where detecting the loss of a whole volume results in the critically failure the backup job.

I was also still hoping you could answer some of the questions I posed in the OP, or at least the first two.

Thanks again,
thesmall
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cobian
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Joined: 31 Oct 2020, 01:25
Location: Sweden
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Re: Backup Kept Running When Disk Was Removed

Post by cobian »

I would be sure that the Safe Mirror Option is enabled.

Questions:
1. Would the setting "Cancel if Volume Shadow Copy fails" have properly handled this issue?

No. If the disk goes offline, the shadow copy goes offline as well.

2. Is there some other setting I should have enabled to mitigate this issue?

Safe Mirror Directory

3. If this is a bug or functional oversight, is there a place to submit bug/feature requests outside of the forum?

You can submit all kind of questions here in the forum. And no, not a bug. The help file has a whole page about mirroring:

"Mirroring
This question has been featured in the FAQ since forever, but people keep asking the same thing over and over again: "I want to make a backup of a directory. I delete some file on the original directory, but the program doesn't delete it from the destination".

Well, let me tell you: A BACKUP PROGRAM IS NOT A MIRRORING PROGRAM. And this is a very dangerous feature to add for a backup program. A backup is a ONE WAY copy. If you delete a file as a mistake or if a virus destroys your data, you will EXPECT to find your files in the destination. If you implement a mirror, you'll find NOTHING there!

Anyway, if you want to take the risk, you can make a mirror by checking the Mirror option in the advanced properties of the task.
"

I added the mirroring option after years and years of people asking for it, but a mirror should never be used as a backup.
--
Luis Cobian
Cobian Backup's creator
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