Managing Oracle Multitenant Databases - OCP: Oracle Database 12c Administrator Certified Professional - page 569

SHUTDOWN ABORT disallows new connections, disallows new transactions, and terminates
current SQL statements. Current user connections are disconnected.
SQL> SHUTDOWN ABORT
ORACLE instance shut down.
SQL>
Notice that there is no indication that the database was closed or dismounted. The next
time you start up the database, it will require automatic instance recovery. Uncommitted
transactions will be rolled back when the instance restarts.
SQL> STARTUP
ORACLE instance started.
Total System Global Area 2471931904 bytes
Fixed Size 2405664 bytes
Variable Size 671091424 bytes
Database Buffers 1778384896 bytes
Redo Buffers 20049920 bytes
Database mounted.
Database opened.
SQL>
Here's an example of what that looks like in the alert log:
ALTER DATABASE OPEN
Sat Nov 30 17:43:33 2013
Beginning crash recovery of 1 threads
parallel recovery started with 3 processes
Sat Nov 30 17:43:33 2013
Started redo scan
Sat Nov 30 17:43:33 2013
Completed redo scan
read 321 KB redo, 114 data blocks need recovery
Sat Nov 30 17:43:34 2013
Started redo application at
Thread 1: logseq 22, block 5188
Sat Nov 30 17:43:34 2013
Recovery of Online Redo Log: Thread 1 Group 1 Seq 22 Reading mem 0
Mem# 0: C:\ORACLE\ORADATA\CONT\ONLINELOG\O1_MF_1_980KX74L_.LOG
Mem# 1: C:\ORACLE\FAST_RECOVERY_AREA\CONT\ONLINELOG\O1_MF_1_980KX9PB_.LOG
Sat Nov 30 17:43:34 2013
Completed redo application of 0.24MB