I've had some good success with updating my code from php 5.6 to php 7.x and updating the driver to use sqlsrv. I typically try to use the CI query method and it works most of the time. I noticed that something weird happens when I try to backup a database though. If I change my code to use sqlsrv_query instead of $this->db->query it works much better. If I try to use the CI query method the backup file will be created and then gets deleted.
I don't see any errors on the server side or php side but the SQL Server just says it failed to backup the database. I would rather use the CI method as I can hide the password in the database.php instead of being in the code directly.
Has anyone else seen this behavior?