How does Linux handle DST (daylight saving time?

I ask you this becouse i have large date base on my servers and if this swich happens instantly one hour on entryes in the data base will pe owerwritten

That suggests you're writing the local time into the database. Regardless of how Linux handles it (and I believe it will do as you say, given that that's how time zones work, basically), you almost certainly shouldn't be writing the local time into your database.

If you write the UTC time instead, then you don't need to care about which time zone your systems are set to, or DST effects. You won't get odd situations where an event X which happened after an event Y is actually recorded with an earlier time, nor will there be any ambiguities. You can adjust the stored time to the local time zone when presenting the data should you wish - and you can do that into any time zone you please.