Hello!

>How can I use the -SE switch with gbak and what advantage/disavantage using

it ?

Using -SE you can perform backup and restore operations on database
server's computer.
It may increase the speed of backup/restore and, on the other hand, decrease
overall server's performance and reduce performance of main database
applications (i.e., SQL quieries will be slower) during these operations.

Note that you may use services to perform backup/restore only on Firebird
with SuperServer architecture - Classic is not equipped with Services API

Sincerely yours,
Alexey Kovyazin
www.ibsurgeon.com
www.ib-aid.com