VSS shadow storage maximum size and backups
I'm putting this in the 2021 forum although I have been making observations on my system running ATI 2019. I have not yet experimented using ATI 2021 but perhaps others could take a look on their systems.
Either using Windows System Protection configuration, or via the vssadmin program, a maximum protection storage size can be set for each drive. I kept finding that my C: drive (the only one with protection on) was constantly having the maximum storage reset to unbounded (100%).
What I found is that
1. Whenever a backup is run and it uses VSS on a drive, it sets the maximum to 100% while it is creating shadow copies.
2. When the backup completes, it resets the maximum size to what it was before, as expected.
3. The unexpected exception occurs when the drive is C: and the backup type is Files and Folders. In this case the maximum is left as 100%.
Is it because C: is the system drive? Is it because C: is the only drive with protection on? Why does the Disk/Partition backup of C: properly reset the maximum size?
"Enquiring minds want to know."


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BrunoC,
I put your issue to test on TI 2021 version 34340. I found that once I enabled System Restore then a backup of either type would push storage size to 100%. After the backups were run the storage size remained at 100% I could only set storage size to a % value after turning on System Restore on a drive or partition. Other drives which had never had System Protection turned on could be resized to any value %, MB, GB, and the setting would remain persistent. If a drive or partition had had at anytime System Restore turned on then only a % value would be persistent and further any shadow copy activity would trigger the setting of the original storage size to be the new setting. In other words if you turn on System Restore on a disk and then set a % value for size that value becomes the default value and anytime thereafter shadow storage is used that value will be what the storage size is reset to and remains persistent.
This suggests that the issue is an MS one. MS knows whats best for the user of course so this is perfectly normal, RIGHT!
I have turned off System Restore on the machine I tested this on. I will leave it on on the machine I use everyday but only for C drive.
I even reset the Registry Value for the storage space % value to 1% and it changed nothing so MS has removed any intervention from the user in managing this space.
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