The alert log file (also referred to as the ALERT.LOG) is a chronological log of messages and errors written out by an Oracle Database. Typical messages found in this file is: database startup, shutdown, log switches, space errors, etc. This file should constantly be monitored to detect unexpected messages and corruptions.
Oracle will automatically create a new alert log file whenever the old one is deleted.
show parameter background_dump_dest;
select value from v$parameter where name=’background_dump_dest’;