Problem description
This article explains the various reasons behind discrepancies in the size of inSync’s backup snapshots for Google Drive versus the actual usage of a user’s Google Drive in Google Workspace
Resolution
Calculation of the Google Apps Data
According to Google’s Documentation: How your Google Storage works:Data belonging to the Google Apps like Google Sheets, Google Docs, Google Slides, etc., before June 1, 2021; DO NOT count towards your Google Drive’s usage in Google Workspace.
Such items created after June 1, 2021 DO get counted towards your Google Drive’s Usage in Google Workspace.
However, with inSync’s backup; each file’s size gets accounted for towards the storage usage calculations for the user’s Google Drive Backup.
Difference in compression mechanism between Google Workspace and Druva inSyc.
Google Cloud Storage has a different rate of compression than Druva.
This also leads to some amount of difference in the size of Google Drive’s usage between these two platforms.
Google Drive Trash Items
When users delete their items in Google Drive -> the items get moved to the Trash folder, which gets cleaned out automatically after 30 days OR can also be cleaned out manually by the end users.
Druva inSync backs up Trash items as well.
Thus, it may happen that the backup job was already completed for the trash items before the items were cleaned out from the Trash in Google Work-space.
In such a scenario, if the end user or the Google Admin is looking at the user’s usage for Google Drive after the trash was cleaned out; they may find a discrepancy with inSync’s backup usage for that user.
Druva inSync’s Incremental Backup Mechanism
Let’s say a user has 10 Files in the Google Drive - each of 1 MB. Thus, the user’s usage in Google Workspace is 10 MB.
inSync backup runs for the user and we backup all of these files. Thus, inSync’s backup too, will be 10 MB (not considering the compression factor in this example).
Now the user modifies One of those 10 files -> leading to the size of the file being 2 MB and overall usage in Google Workspace being 11 MB.
When inSync runs its incremental scan, inSync will check for modified items and will back up the modified items in full.
This means the file which was 2 MB, will be backed up as a new file and the rest of the 9 files will NOT get backed up as they were not modified since the last backup.
Now in this scenario, the first backup in point # 2, led to the user’s usage in inSync being 10 MB.
But in the next backup in point # 5, inSync backed up the 2 MB file in full -> leading to the overall usage in inSync being 10 + 2 = 12 MB.
Thus, when items in Google Drive are modified frequently, you may notice a discrepancy between the size of Google Drive across the two platforms.
Backup shared data owned by other users
Within the inSync profile -> SaaS Apps -> Google Drive -> a checkbox labeled as “Backup shared data owned by other users” allows you to back up the data that resides in the “Shared With me” section of the user’s Google Drive. Check the screenshot below:
inSync’s backup code works differently on the basis of this checkbox when it is checked and when it is unchecked.
Please check the following document on: Druva inSync’s mechanism of backing up Shared Data from Google Drive
In case of storage statistics discrepancies for Google Drive backups, ensure to check all of the above listed information.
If this does not help answer the discrepancies, then please reach out to Druva Support for further investigation.