The support forum

Backed up files integrity and other questions

AlexS :

Jun 19, 2015

Hi Alex,
1. Sorry if it is dumb question, but is created (backup) files checked? I mean is it assured in any way that backup copy of file identical to source file and not corrupted?
2. What happens if files at backup destination changed between backups (let say accidentally by user)?
3. If i use continuous backup, and backup of some file failed. Let say because of network problems.  I mean will the program retry to backup this file later also if file not changed? With manual backup the program not retrying to backup such files. I think it will be good if program will retry at least once.
THank you.

Alex Pankratov :

Jun 19, 2015


1. Valid question. Backup verification is *the* outstanding feature at the moment and it should be done within one or two releases. Basically the plan is to allow scheduling bitwise source/backup comparison similarly to how you can now schedule the actual backup.

2. The answer depends on the "Detecting changes" setting. If it's set to "re-scan", the modified backup copy will be detected and it will be updated to match the source. If the setting is at "use snapshot", then nothing will be done until the source file is touched.

3. Yes, it will retry the backup. At least at should. If it doesn't, then I need a bit more of the context (including the error logged for the file).

AlexS :

Jun 19, 2015

1. So currently after file created at backup destination it not checked to be exactly like source? If not, i think it will be good to enable such check at least as option. I mean besides option to run backup comparison task.

Harry :

Sep 02, 2015

Hi,

For non-continuous backups i.e. those that are scheduled or every x hours, is there/can there be an option to auto-retry up to x times if the backup fails? This looks like a fantastic bit of software and we are looking for a robust solution to backup over a flakey VPN connection. Error recovery/retry is a must.

If not, perhaps this can be scripted with PowerShell/command line? If the software is run by command line, does it return a value for fail/success? I.e. could we script our own retry mechanism?

Thanks,

Harry

Alex Pankratov :

Sep 02, 2015



@AlexS - I thought I replied, sorry for the mess up. Correct, at the moment there is no built-in function to compare source with destination bit by bit. Tentatively, it will be added in the release after the next one (R76).

I've been sketching this feature and one thing I realized is that you don't really want to compare destination to source per se. You want to compare destination *and* source to the state of the source as it was during the last backup. That's because data corruption may occur at either end and you will end up copying junk over pristine data if it was the source that got corrupted.

Alex Pankratov :

Sep 02, 2015



@Harry - there's no built-ini auto-retry logic in the app. But you can indeed cook something up with a bit of scripting. You can kick off a backup through command line [1], but in order to understand if it completed successfully you will need to use the post-backup script [2].

[1] https://bvckup2.com/support/forum/topic/411
[2] https://bvckup2.com/support/forum/topic/98

I can't promise it will be done, but just to clarify - basically you'd like for the app to re-run the whole backup N times if it doesn't complete cleanly? Or would you prefer for it to retry each backup step up to N times before failing it (and potentially aborting the backup)?

AlexS :

Sep 02, 2015

@Alex Pankratov
1. My point was to check that copied file identical to original immediately after copy completed, to ensure that file copied properly.
2. Data corruption at source is a real problem, and for this reason simple synchronization as done by bvckup2 not a best backup option, at least without some type of versioning. Of cause it still useful in many cases.

Alex Pankratov :

Sep 03, 2015

Hmm... there indeed is a separate data corruption risk associated with the actual copying, e.g. if the data ends up going through a faulty RAM. As opposed to corruption risk for the at-rest data due to media deterioration and such.

That's a good comment, Alex, thanks.

Bomba :

Oct 22, 2015

Is possible, before backup file recently changed, make a compare file? My problem is many of users have .pst opened in Outlook and they are ALWAYS updated (only by date), but the file itself is not different than the older one.

I want to compare the two version before update it

Alex Pankratov :

Oct 22, 2015

That's exactly how delta copying work. It scans through the entire file and checks which blocks have changed. If none changed, nothing gets copied.

New topic

Create
Made by IO Bureau in Switzerland
Support

Updates
Blog / RSS
Follow Twitter
Reddit
Miscellanea Press kit
Testimonials
Company Imprint

Legal Terms
Privacy