My understanding is that feature (database mirroring) was deprecated many years ago, for availability groups. There were some limitations in the Analytics area, but that customer was using another solution for most of that anyway. There were also some features of SQL Agent that were discarded (scheduling events or something) but in each case there is some officially supported route to accomplish the same task.

You can find most of the material we reviewed in the official MS documentation:

https://docs.microsoft.com/en-us/sql/linux/sql-server-linux-...

For example, here's the note about deprecating database mirroring:

https://docs.microsoft.com/en-us/sql/linux/sql-server-linux-...

> Database mirroring, which was deprecated in SQL Server 2012, is not available on the Linux version of SQL Server nor will it be added. Customers still using database mirroring should start planning to migrate to availability groups, which is the replacement for database mirroring.