Differential Backups

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Re: Differential Backups

Postby DrTeeth » Wed Jun 06, 2018 10:55 pm

On Sun, 3 Jun 2018 16:26:17 EDT, just as I was about to take a herb,
"Ed" disturbed my reverie and wrote:

>My question is if you have a couple differentials and only one full, do you
>always use just the last differential and point it to the full or use both
>differentials ?

Sorry I missed this from my last message.

I have a backup folder with my full backup in it. That has two
sub-folders. I use one until I would have to scroll to see any more in
the "select existing backup to use", I then swap over to the next
folder and start again. I generally make a full backup after changing
the partitions as one has to as any differential or incremental will
fail. The other reason for making a new full is after a defrag.

The first backup in each of the sub-folders is a differential, and all
the others are incrementals. Here is a screenshot of my folders
https://tinyurl.com/ybg9qe7x.

I use this method as I can clear out one subfolder when I have a few
days of backups in the other.

I can restore from any of the differentials and incrementals.

If things are still not clear, I am more than happy to make a
screencast for you.
--
Cheers,

DrT

"If you want to find out what is wrong
with democracy, spend five minutes with
the average voter." - Winston Churchill
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Re: Differential Backups

Postby f64 » Sun Dec 30, 2018 5:29 pm

My pc has two drives; a 500 GB SSD (Basic MBR) containing the OS and a 1TB HD (Basic MBR) containing Data. My two identical external drives are 3TB (GPT) HD and
I change the GUID when I copy one backup drive to the other to differentiate between them.

My full and differential backups of both OS and Data drives are in the same folder on the backup drive. When I make a changes only backup,
I name it the same as the last changes only backup, so I only ever have one full and differential backup of each drive.

I recently restored the data drive using IFD by first restoring the full backup and then restoring the differential.
So, I could have just chosen the differential (without the multi-pass option) and the restore would have been faster?

Also, when I went to make another backup after the restore, Windows 7 kicked my External backup drive offline due to a signature conflict.
Should I have chosen the Restore Disk Signature option to prevent this?
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Re: Differential Backups

Postby TeraByte Support(PP) » Sun Dec 30, 2018 11:53 pm

f64 wrote:
> I recently restored the data drive using IFD by first restoring the full
> backup and then restoring the differential.
> So, I could have just chosen the differential (without the multi-pass
> option) and the restore would have been faster?

Correct (it would have been a single restore).

> Also, when I went to make another backup after the restore, Windows 7
> kicked my External backup drive offline due to a signature conflict.
> Should I have chosen the Restore Disk Signature option to prevent this?

You are copying one backup drive to the other and normally change the GUID? Did you forget to select that option? I assume the collision was with the other external backup drive. Why don't you just alternate between them when you create the backups instead of copying them? Or you could copy the new backup image files to the other drive (replacing what's there) instead of copying the drive.
Paul Purviance
TeraByte Support
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Re: Differential Backups

Postby f64 » Mon Dec 31, 2018 2:19 am

I did not forget to change the GUID for the Copy of the backup drive.

My regular backup involves several pcs to my external backup drive #1, in their respective folders. Then I periodically use the Copy function to duplicate external backup drive #1 (3 TB) to external backup drive #2 (3 TB)
and since they're GPT drives, I must change the GUID when I do the Copy, so I can tell which is #1 (more recent); else they would have the same GUID and I can't tell which is which if they're both running/connected. I learned this long ago.

The problem happened later that same week after doing a restore from ext. drive #1. I may have even done the restore from #2, IDK. I had #1 running/connected as I often do before restarting (IFD media) for the
regular backup of MBR drives, which failed (don't recall the error). When I went to look at #1 with TBIView in Win 7, I discovered it was offline and my partitions were borked.

So, I'm asking/assuming I should prevent this with the "Restore Disk Signature" option as per the instructions (p. 78 v 3.12):
"If you are restoring a partition that had been assigned a drive letter in Windows and you wish to keep that drive letter assignment, select this option."
My external drives don't have letter assignments.

I was going to test this out since I have a Copy/Clone of my external backup drive, but because I'm not completely sure what went wrong, thought it would be better to ask first.

Thanks
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Re: Differential Backups

Postby TeraByte Support(PP) » Mon Dec 31, 2018 9:16 am

The "Restore Disk Signature" option would restore the signature saved in the backup being restored to the destination drive. In your case, it would restore the signature of the "Data" partition's drive. Normally, that signature wouldn't have changed so it wouldn't affect anything. Using the option also wouldn't affect the external drive since it is the source of the backup.

Normally, you can bring the drive with the collision back online in Disk Management and it will fix up the GUIDs, though you may need to adjust drive letter assignments.

How would you look at #1 with TBIView in Windows 7 if you don't use drive letters on the external drives?

Personally, I would avoid changing the GUIDs every time as this makes Windows reassign letters for it (among other things). You could still do the disk copies like you do, but use the global "Prefer Target Disk ID on Change" option to retain the existing "different" ID.
Paul Purviance
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Re: Differential Backups

Postby f64 » Mon Dec 31, 2018 7:31 pm

I meant to say "I" didn't assign a drive letter to the backup drives, only a label, so Windows is applying the next available letter. As for the offline drive,
I brought it back online but it had unallocated space; ie. my data was gone. I'm not really sure if it was something I did wrong in the restore, but
I intend to test it again with a small drive. It could have been an interface hiccup that caused the problem. Another good reason to have more than one backup. :)

Thanks again for the help. I've used IFD/IFW many times in the past for restores and it has always been superb.

edit: I tested a small drive and my Storage drive using IFD restore and couldn't duplicate the error, so it must have been a hardware anomaly. Also, I did assign a drive
letter to my Storage drive, apparently, and finally, there is only the option in my case to change GUID on restore, not Restore Disk Signature, but I didn't use either
option and it works fine.
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