The alert log isn't very helpful...

(As the DB starts)

Tue May 25 02:00:11 2004
ARC0: changing ARC0 KCRRSTART->KCRRACTIVE
ARC0 started with pid=8
Tue May 25 02:00:11 2004
ARCH: Initializing ARC0
ARCH: ARC0 invoked
Tue May 25 02:00:11 2004
ARCH: STARTING ARCH PROCESSES COMPLETE
Tue May 25 02:00:11 2004
ALTER DATABASE MOUNT
Tue May 25 02:00:11 2004
ORA-09341: scumnt: unable to mount database
OSD-04400: unable to acquire internal semaphore for process
O/S-Error: (OS 183) Cannot create a file when that file already exists.

Tue May 25 02:00:11 2004
ORA-1102 signalled during: ALTER DATABASE MOUNT...
Tue May 25 02:00:12 2004
ARC0: Archival started


and it hangs here. Just brute rebooting the server causes both DBs to start fine, with this alert log:

ue May 25 09:50:28 2004
ARC0: changing ARC0 KCRRSTART->KCRRACTIVE
ARC0 started with pid=8
Tue May 25 09:50:28 2004
ARCH: Initializing ARC0
ARCH: ARC0 invoked
Tue May 25 09:50:28 2004
ARCH: STARTING ARCH PROCESSES COMPLETE
Tue May 25 09:50:28 2004
alter database mount exclusive
Tue May 25 09:50:29 2004
ARC0: Archival started
Tue May 25 09:50:34 2004
Successful mount of redo thread 1, with mount id 1461560362.
Tue May 25 09:50:34 2004
Database mounted in Exclusive Mode.
Completed: alter database mount exclusive
Tue May 25 09:50:34 2004
alter database open
Picked broadcast on commit scheme to generate SCNs
Tue May 25 09:50:36 2004
Thread 1 opened at log sequence 6439
Current log# 1 seq# 6439 mem# 0: I:\ALPS\ALPSLIVE\ALPL_REDO01.LOG
Successful open of redo thread 1.
Tue May 25 09:50:36 2004
sql: prodding the archiver
Tue May 25 09:50:36 2004
SMON: enabling cache recovery
Tue May 25 09:50:36 2004
ARC0: received prod
Tue May 25 09:50:39 2004
SMON: enabling tx recovery
Tue May 25 09:50:39 2004
Completed: alter database open
Tue May 25 10:00:59 2004
LGWR: prodding the archiver
Tue May 25 10:00:59 2004