[Mirror ->] Old data (right side) was deleted after run backup

[petergiang]

Dear all member,
I have problem with data backup.
I used Mirror method for backup.
If I delete the data on left side, the datawill be lost on right side
How to fix this problem.
Thank you!

[xCSxXenon]

That is not a problem, that is how a mirror backup works. Look into "update" and versioning.
https://freefilesync.org/faq.php
https://freefilesync.org/manual.php?topic=all

[petergiang]

To update right side without lost old data when I delete data at left side, is there any method to do this?
Pls refer config as attached image and give me your advise

[xCSxXenon]

That is not a problem, that is how a mirror backup works. Look into "update" and versioning.
https://freefilesync.org/faq.php
https://freefilesync.org/manual.php?topic=all

Read?