Deleting files to shrink Acronis True Image backups

I’ve been using Acronis True Image Home to make periodical snapshots of my system partitions, in case I ever have to recover from disaster (which happened a few times in the past). There are typically directories on my system partition, which I do not want to back up, since they are not really part of the system state, not unique to my computer, and yet take a lot of space (for example – games, which can always be reinstalled, SDKs which can be redownloaded, temporary files which just happen to be there at the time I want to back up, etc.)

Conveniently, True Image has settings to exclude any files/folders when backing up partitions. They’ve always worked for me, until this recent time, when for whatever reason, True Image ignored my exclusions, and included every single file in the backup archive, which made it ~500 GB instead of the expected ~60 GB. I learned that this sometimes happens when sector-by-sector mode is selected, and that True Image sometimes forces this mode when it detects errors on the partition. However, in my cases, the partition seemed error-free (confirmed by CHKDSK) and nothing in the logs suggested that sector-by-sector mode was used. Suspecting a glitch, I re-ran the backup operation, but the result was the same.

Unable to figure out why True Image ignores my exclusions, I decided to try a different approach – manually remove the unnecessary files from the backup (.TIB) after creation. Surely, it should be possible? Turns out it’s not always so easy.

Acronis allows .TIB files to be mounted as partitions; however as of True Image 2015, the ability to mount them in read-write mode (which allows changes) has been discontinued. Fortunately, I happened to be still using True Image 2014 for this system, so the feature was still available.

However, when files are deleted from a .TIB, it does not cause it to shrink. Instead, Acronis creates an incremental backup, which in this case is just another small .TIB, with information about which files were removed from the first archive. However, the original huge .TIB is still there, and the backup cannot be used without both files present.

At this point, users of the Acronis Backup & Recovery business product can use the
“Vault” feature to export such a backup, which causes Acronis to generate a new single-version backup without the deleted files. However, the Vault is not available in True Image Home, and I could not find an obvious way to achieve the same functionality, at least not in True Image 2014. In the end, I used a “dirty” two-step trick to shrink the archive:

  1. Convert the original True Image backup (.TIB) to Windows backup (.VHD) via the “Acronis Backup Conversion” feature on the “Tools and Utilities” tab. This forces Acronis to recreate the archive from scratch, and the deleted files/directories will not be there, so they will not take any space. Keep in mind that .VHD files are not compressed, so the .VHD will be larger than the .TIB would have been.
  2. Convert the .VHD back to .TIB via the “Windows Backup Conversion” feature on the “Tools and Utilities” tab. This creates a fresh .TIB, which is equivalent to the original, incremental backup, and without extra space consumed by the deleted files. It is also compressed, like every True Image backup, so for archival purposes it is better to do this step than to stay with the .VHD.

To confirm that all went well, I ran the backup validation built into True Image on the new archive, and also explored it to confirm it includes all the files/folders I wanted, and only them. Its final size was what I would expect (~60 GB; the uncompressed .VHD was ~110 GB), so the end result is probably what True Image would have done, if it had not ignored my exclusion list in the first place.

That’s it. I hope this little write-up might be useful to someone stuck in a similar predicament with one of Acronis‘s backup products. I like Acronis products a lot, because they tend to be very reliable, and even if something does not always work exactly as it should, there are typically enough features providing workarounds to achieve the same end, as was in my case. Acronis also has a great knowledge base and forum, which contain both up-to-date information, as well as archival knowledge about past products.



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