Same sync job, 3 destinations
- Posts: 1
- Joined: 21 Sep 2026
Hi, I have set up a MIRROR job from a folder on my computer to a folder on an external driver (H:). I have not set any versioning etc. I have 3 USB drives which I plug in, rotating weekly. Is it OK if I change a USB drive and then run the job, next week change to another USB drive and run the job?
- Posts: 184
- Joined: 5 Jan 2024
Yes. That is a perfectly reasonable way to use a FreeFileSync Mirror job with rotating USB backup drives.
Each week you can:
1. Plug in that week's USB drive.
2. Make sure Windows assigns it H:.
3. Run the same FreeFileSync Mirror job.
4. FreeFileSync will compare your source folder with whatever is currently on that USB drive and make the USB copy match the source.
It doesn't matter that a particular USB drive hasn't been connected for two or three weeks. When you reconnect it, FreeFileSync compares the current source against that drive and brings it up to date.
One important warning about Mirror
Because you're using Mirror, deletions are mirrored too. For example:
Week 1: Important.docx exists on the computer and gets copied to USB #1.
Week 2: You accidentally delete Important.docx from the computer.
Week 4: You reconnect USB #1 and run Mirror.
FreeFileSync will normally delete Important.docx from USB #1 as well.
So your three-drive rotation gives you some protection because an older disconnected drive may still contain the deleted file, but only until you run the Mirror job against that drive.
If these three drives are intended as true backups rather than simply synchronized copies, I'd consider enabling Versioning. Then files deleted or replaced on the computer can be retained in a versioning folder instead of simply disappearing from the backup.
Also, I'd strongly recommend assigning each of the three drives a permanent drive letter in Windows so they don't unexpectedly become I:, J:, etc. You can even give all three drives H: because only one will normally be connected at a time.
Each week you can:
1. Plug in that week's USB drive.
2. Make sure Windows assigns it H:.
3. Run the same FreeFileSync Mirror job.
4. FreeFileSync will compare your source folder with whatever is currently on that USB drive and make the USB copy match the source.
It doesn't matter that a particular USB drive hasn't been connected for two or three weeks. When you reconnect it, FreeFileSync compares the current source against that drive and brings it up to date.
One important warning about Mirror
Because you're using Mirror, deletions are mirrored too. For example:
Week 1: Important.docx exists on the computer and gets copied to USB #1.
Week 2: You accidentally delete Important.docx from the computer.
Week 4: You reconnect USB #1 and run Mirror.
FreeFileSync will normally delete Important.docx from USB #1 as well.
So your three-drive rotation gives you some protection because an older disconnected drive may still contain the deleted file, but only until you run the Mirror job against that drive.
If these three drives are intended as true backups rather than simply synchronized copies, I'd consider enabling Versioning. Then files deleted or replaced on the computer can be retained in a versioning folder instead of simply disappearing from the backup.
Also, I'd strongly recommend assigning each of the three drives a permanent drive letter in Windows so they don't unexpectedly become I:, J:, etc. You can even give all three drives H: because only one will normally be connected at a time.
