Problem with Differential Backups

I have recently started using Acronis True Image, version 9, build 2337. I was previously running version 8, build 937. The reason I've upgraded is so that I can create differential image backups. With version 8, I had been creating incremental image backups.

I created one full image backup of my C partition to a backup USB drive. I then set up the scheduler to run a daily differential image backup. When I looked at the daily differential image backups, their sizes were what I expected, i.e. each daily differential backup image was slightly bigger than the previous day's backup image. I then had Acronis check the 4th backup (I assumed that it was checking a combination of the original backup + the 4th backup) and it said that everything was OK. I then moved the second and third differential backups to another folder, and then had Acronis check the 4th backup image again. This time, it could not check the image, and insisted that I insert the third backup.

Then I attempted to restore a file stored in the 4th image, using only the original full backup and the 4th backup, and Acronis did this with no problem.
If I understand the way the program is supposed to handle differential image backups, for either checking images or restoring images, it should only require the original full backup + one differential backup.

Is this a bug in the image checking part of Acronis True Image or is Acronis effectively creating incremental backups, i.e. each differential backup is not based on the original full backup, but instead is based on the last differential backup. This would certainly expain why the image checking part of the program requires all the backups.

Therefore, if I actually want a daily differential image backup, the only way to do it is to move or delete the previous days differential image backup before the new one is created. This is assuming that the scheduler is not keeping track of the previous differential backups; if it is, then I'm not sure what will work - possibly manually creating each day's differential backup, after I move the previous day's differential backup to another location.

 

Are you sure that you are using the full backup as the basis for each differential? I ask because it is possible to do a differential on a differential and if the differential filename was used as the basis, you would get the result you have experienced.

For further explanation, take a look at post 6 in this thread and Kirill's clarification a few posts later.

 

As far as I am aware, I am using the full image backup as the basis for each scheduled differential image backup. However, all I can do is select the full backup as the basis for all the scheduled backups, when I first create the scheduled differential backups. Beyond doing that, there doesn't seem to be any option to specifically tell the program not to use the differential backups it creates as the basis for future differential backups.

 

Hello HW11,

Thank you for choosing Acronis Disk Backup Software.

Could you please clarify whether you choose Files and folders option to create an image of your partition or The entire disk contents or individual partition option?

Please note that if you choose The entire disk contents or individual partition option to create the full image, you can delete any previously created differential images without any problems. Your last differential backup will be restored without any previous ones.

Thank you.
--
Tatyana Tsyngaeva

 

To clarify, I am not using the Files and Folders option. I am selecting the option which says "The entire disk contents or individual partitions."

I haven't tried to do a full restore, so I can't be sure whether it would work the way you and I would both expect it to. However, when I check the archive of the backup, the program insists on the presence of the entire series of images, which it shouldn't require, e.g. if I leave backup.tib (the original full backup) and backup.tib4 (the 3rd differential backup) alone in the file folder, when the program checks the archive, it will ask for backup.tib3 (the second differential backup).

I realize that I may be doing something wrong in terms of how I am creating the differential backups, but I can't find any way to tell the program that I want each successive differential backup to start with the original full backup, so I have assumed that it does this automatically.

 

Within the Create Backup Wizard, on the Backup Archive Location screen, open the File Name drop down box and make sure that you select the original, full backup: it will be the very earliest in each series of backups bearing the same name. As differentials or incrementals are taken, TI appends a number to the original name so you can always work out exactly where each stands in relation to the others.

 

Thanks for your efforts to get to the bottom of this problem. What you have described is exactly what I am doing, unless I have inadvertently selected the wrong file name or unless the program has a mind of its own. As far as I am aware, I am selecting the name of the original full backup and then scheduling a daily differential backup, so I don't have an opportunity to inadvertently select subsequent differential backups.

 

So, you're scheduling the differentials. Hmmm... This is beginning to sound like there may be a, dare I say it, bug. I'd say that your assumption that each scheduled differential would be automatically based on the nominated full backup is completely logical, but perhaps that's not how it actually does it. It certainly sounds like scheduled differentials are each based on the preceding differential and are actually incrementals. Not at all what you would expect!

I'm afraid that because of other things going on on my system at present, I can't check this out myself, but perhaps someone else could have a look at it??

 

I have now performed a further test. I have kept the full image backup, but I have moved all the previous differential backups to a new folder. I then manually created two new differential backups, making sure that each time I selected the original image as the base image.

The first differential (ending in 2.tib) was 1,207,597 KB and the second differential (ending in 3.tib) was 1,209,337 KB.

I then moved the first differential (the one ending in 2.tib) to another folder.

I then selected the option to "Check archive", and the only images available were the original full backup + the second differential (the one ending in 3.tib).

The checking started, and then after a short period of time, a warning message appeared "W00040011: Please insert the media marked volume 2".

The checking of differential image archives is definitely not working the way I would expect it to.

 

I have now done a further test. First, I checked to see what Acronis actually says and in the Schedule Task Wizard under Archive Creation Mode, when Differential Backup is selected, it says "Backs up only changes occurred since a last full backup." and it says this whether I select the full backup archive as the base or a differential backup archive. Therefore, this would indicate that the Acronis programmers are doing differential backups the way everyone else does, i.e. a differential backup always uses the previous full backup as the base.

I also ran a test where I specifically selected a previous differential as the base, and I had it create the new archive 45 minutes after the last differential archive was created. The previous differential archive was 1,209,337 KB and the new archive was 1,209,861 KB. This would very strongly indicate that Acronis True Image is always doing a differential backup using the last full backup as a base, since I hardly used the computer between the two differential backups.

 

If I'm reading correctly, it appears that you performed your latest tests by doing manual, not scheduled backups. I don't think there's too much doubt that if you are doing the backup manually, then TI will base the differential on the full unless you specifically tell it to do otherwise - at least that's what I've found. Take another look at the Support posts referred to in my post #2 in this thread. It did seem though, that your original problem occurred when the differentials were scheduled rather than manual.

When True Image refers to 'volumes', volume 2 isn't necessarily disk 2. If you check what's on the disks, you may find that there is more than one file on each. TI will call them volume, 1, 2, 3 etc., so when it is referring to volume 2, it may mean disk 1.

 

To clarify, I did each of the latest backups as one time scheduled backups (so they were not manual backups), and all my backups are to a USB hard drive, so that volume 2 presumably referred to the file ending in 2.tib.

As far as I can tell, True Image does differential backups exactly like any other program, i.e. all differentials include all changes since the last full backup. If anyone has managed to make True Image create any other sort of pseudo differential backup, I'd like to know exactly how it was done.

The problem appears to be that, when True Image attempts to check a differential backup, the programmers decided to use the same routine as they were already using for checking incremental backups. Therefore, the program demands all the intermediate differential backups even though they are irrelevant.

 

Just a thought... after you removed the 2.tib file, what if you rename the 3.tib to 2.tib?

 

Never mind. I tried it myself. It didn't work. After renaming the 3.tib file to 2.tib, TI generated an error while verifying the file's integrity. The 3.tib file seems to contain info about previous backups (the base and 2.tib), so TI wouldn't accept it as the 2.tib file.

However, I CAN recover from the 3.tib backup point (both entire hard drive or selected files) using just the base .tib and 3.tib file (correctly named), without the 2.tib file. So differential backups are still usable until this bug is fixed. Just don't set the option to verify archive after each differential backup.

 

Thanks for the assistance. I had already tried renaming a tib file, and it didn't work for me either.

I also successfully recovered one file, but I thought that if I wanted to restore an entire image, then True Image would automatically check the archive, whether I want it to or not, and I would then run into the same problem as before. Did you actually successfully restore an entire image, e.g. the base and the 3.tib files?

 

This is definitely beginning to look as if there is an anomaly (?!) in the Differential image verification routine.

Hopefully an Acronis Support Moderator will pick up on this thread again and get their Development Team to check it out.

Regards

 

Yes, I did. TI restored an entire hard drive from the base .tib and 3.tib file, without the 2.tib file (which I have moved elsewhere).

P.S. Build 2337.

 

Hello everyone,

Thank you for choosing Acronis Disk Backup Software.

Please accept our apologies for the delay with the response.

I'm afraid that what you have found is a known problem of Acronis True Image 9.0 and in fact can be called a "bug". The point is that the current version of Acronis True Image 9.0 requires all previously created differential images in order to verify the integrity of the latest one. However, in order to restore or plug the latest differential image you still need only this particular differential image and the intial full image. Our Development Team is aware of this issue and will do their best in order to fix it as soon as possible. We are really sorry for your inconveniences.

Thank you.
--
Alexey Popov

 

Hello Allexey,

Thank you for your honest answer. Hopefully the Development Team succeed in sorting out this "bug" (along with a number of others!!) real soon.

Kind regards

 

Alexey, thank you for the response. Now that I know what's going on, I'll set up my differential backup procedure to work around the limitations of the current version.

 

Are you sure you are actually running differential backups? I am experiencing the problem described in this post:

https://www.wilderssecurity.com/showthread.php?t=98614

whereby I select Differential as the backup mode, but then in the final confirmation screen before clicking Finish, the mode has changed itself to Incremental. When I step back to the Archive Creation Mode page and re-select Differential, then step forward again, the final screen then retains the Differential mode.

Just a thought....

 

Yes, as far as I can tell, Acronis is creating differential backups (as I would expect with differential backups, each backup is larger than the previous one). If it matters, I am using version 9, build 2337.

 

Alexey, I have now downloaded and installed build 3567. I then tried to verify an existing combination consisting of a base image and differential image #15. At first, I thought that everything was finally working, but then the program asked me to insert image #14. So I assume that this is still not fixed; unless by some chance it is only fixed with new differential images.

 

Hello HW11,

Thank you for choosing Acronis Disk Backup Software.

Please note that the issue with differential images has been already fixed. However, you should create the new differential images with the latest build in order to make sure that Acronis True Image works correctly on your computer.

Thank you.
--
Tatyana Tsyngaeva

 

I have now used build 3567 of TI Home to create a full backup followed by 2 differential backups. I then moved the full backup + the differential backup numbered 3.tib to a separate folder. I then attempted to verify the image. After a minute of so, Acronis displayed this message, "W00040011: Please insert the media marked volume 2" and it offered me the choice of retrying or cancelling. Accordingly, it would appear the problem is definitely not fixed.