ATI v2016 disk space report is wrong, instructions to delete backups unclear

"entire pc" is designed to backup all internal drives of the system and may contain other disks than intended.  I would recommend you change this from "entire pc" to "disks and paritions" and only select the disk or disks you intend to specifically backup.

Your current backup shows it is going to backup approximately 1.5TB of data.  Your destination shows it is 1.8tb but only has 335GB free.  Clearly, you cannot backup 1.5Tb to 335Gb of space so you need some more room

Agreed that the documentaion is not very clear in the deletinig of backups.  As of 2015 to current - Acronis removed the individual backup cleanup capability from within the app.  The recommended way to do this is to use an automated cleanup rule in your backup task.  In your case, if your main drive and backup drive are roughly the same space, you're really only ever going to be able to have 1 full backup.  Ideally, you want your backup drive to be 3-4 times larger than the original to allow for multiple backups.  Also, many people don't realize that each version chain, is only considered complete when teh next full backup has completed.  As a result, if you have a 1TB full backup and say, 100Gb of incrementals, you'll need a minimum of another 1TB before any cleanup rules can take place.

In this case, since it sounds like you dont have a cleanup rule in your backup task already, you could manually delete the backup .tib file in Wndows explorer, but would need to immediately run a validation on the backup to update the acronis database that the file has been moved.  Essentially, Acronis will tell you the file i smmissing and ask you to either navigate to where it was moved, or to "ignore" it.  If you ignore it, then it removes it fro the backup database.

George, welcome to these user forums.

Please be aware that by selecting 'Entire PC" this can include all currently connected disk drives in your system, not just our OS SSD and other internal drives.

I would recommend moving your mouse over the Source selection area in the Acronis GUI and using the option for Disks & Partitions instead of defaulting to 'Entire PC', as this will allow you to select the specific entire disk drive(s) that you want to include in the backup file.

With regards to managing your backup files and therefore the available free space on your backup drive, you should use the auto cleanup options provided in the Backup configuration settings to do this.  My personal preference is to use the option to Store no more than X recent version chains as this then allows me to keep control of the backup file size.

A backup version chain is a full backup plus all associated incremental or differential backups, so if you define to create a new full backup after making 5 incremental backups, your version chain = 1 x full plus 5 x incremental backup files.

Note: Acronis will only delete old backup version chains when the next full backup for a new chain has been successfully created, so you need to allow to have X plus 1 backup chains space available.

Finally, see the online ATIH 2016 User Guide: Backing up disks and partitions  and also Custom schemes for more information on the above.

Bobbo - Thank you so much for this rundown.  Will do as you suggest and report back.

Steve - As with Bobbo, many thanks for explaining the way Acronis works and for the suggested cures.  Of particular help is this: << Acronis will only delete old backup version chains when the next full backup for a new chain has been successfully created, so you need to allow to have X plus 1 backup chains space available >>.  I think I follow the logic of this . . . in so doing, no backups are lost before a new backup is made, just in case.  Not much help in saving space the first time around, but after that it should (save space).  The problem is in finding space to do the cleanup.  I'll get back to you both after working on it.

Thanks again.

Bobbo & Steve -

I now realize I left out a crucial piece of information in my initial post - that I'm backing up to a 2 Tb external drive.   Very sorry about that.  Per Steve's suggestion I switched source to the 2 internal drives instead of "Entire PC."  The size went from 1.5 Tb down to 448.8 Gb.  Still, there was not enough room on the external drive to take the backup.  So my plan is to delete everything on the external drive and start over again, using the "Differential" backup scheme.  Backups are set to run every day at the same time, and a full backup every 7 differential backups (i.e. once a week).  In between, the 2 Tb internal is defragged every Wednesday (NO defragging of the SSD).  Having read the cautionary note about defragging I'm still uncertain about how Acronis will deal with that.

Please advise as to how to Validate the record after deleting all from the external drive.  The help file says to click on "Backup" on the side bar but there is no such choice.  It also says to click on the Recovery tab but there is no such tab either.  Help!

George, to Validate your backup task after deleting backup files from your external drive, look to the right of the task name and click on the (V) icon which will then show you additional options, including one for Validation.

If you defragment any of your source drives then any subsequent backups may be significantly larger, this is because Acronis is looking for changes at a sector level and defragmentation touches lots of sectors in the process of moving and consolidating files on your disk drive.

In additon to Steve's note, if you remvoed the backup in Acronis already (not sure if you did or not), by selecting the option to only delete settings (which leaves the backup on the drive), you'd need to add the backup again, then validate.  Otherwise, just start with a new backup task and start clean if the plan is to wipe the existing backup .tib files from the drive anyway.  A small pain to reconfigure a new backupk, but starting "fresh" doesn't hurt when you're starting over anyway.