Cloudiway supports delta migration for all kinds of data (mails, files, collaborative sites etc.).
This article describes how delta migration works when migrating Google Drive or OneDrive.
Delta migration during file migration
When Cloudiway migrates files between Google Drive, OneDrive or SharePoint Online, the ID of the files and the date of modification are stored internally.
The next time a migration is triggered, only the delta is migrated: Cloudiway performs a database lookup to verify if the file has already been migrated.
- If the file ID does not exist in the cache, Cloudiway migrates it.
- If the file ID is present in the cache, Cloudiway compares the last modification date and the internal value stored. If the source file is more recent, the target is overwritten. If the target supports versioning, Cloudiway is able to create a new version of the file.
When Cloudiway migrates a user for the first time, it unconditionally pushes all files found at the source to the target. If a file already exists at the destination with the same name in the same folder, it is overwritten.
For example, imagine that a user migrates files manually. If the user modifies a file at the target, and then the administrator migrates the user through the platform, the first pass of the migration will overwrite the target files with the source files.
To prevent this, Cloudiway has an option to keep existing files.
Keep Existing files
See how it works: Keep existing files during migration
During the first pass, existing files are not overwritten: they are pushed and renamed with the_OLD suffix.
If, during a second pass, the file is modified at the source and has a more recent modified date than the target, then the target would be overwritten (this means that a user modifies the same file at the source and at the target manually). During the sync, the more recent version is kept.
Note for permission migration
- During delta passes, permission changes are not remigrated if the file has not been modified. Reason: if the modified date remains the same, Cloudiway considers the file unmodified and ignores it. If a permission change has occurred, this will not be pushed.
- If the file has been modified, it will be pushed again to the target and the permissions will be reapplied.
Files or folders deleted at the source are not propagated to the target during delta passes.