> After this step firebird.log contains:
>
> SRV Wed May 01 14:54:40 2019
> Sweep is started by SWEEPER
> Database "EMPLOYEE"
> OIT 156, OAT 20157, OST 20157, Next 20157
>
> SRV Wed May 01 14:54:41 2019
> Shutting down the server with 1 active connection(s) to 1 database(s),
> 0 active service(s)

Why it was shut down ?

> SRV Wed May 01 14:54:41 2019
> Error during sweep:
> connection shutdown

It is OK, sweep was detected database shutdown and stop itself correctly.

> and result of "gfix -validate -full -no_update EMPLOYEE":
>
> Summary of validation errors
> Number of index page errors : 1

What is in firebird.log ? Are you sure there was no errors before the sweep ?

> So, I wanted to see this! Automatic sweep destroy the database. And easy
> to reproduce. Too easy! :-(

Why do you think database is "destroyed" ? Too strong statement without answes on my questions above.

Regards,
Vlad