[oracle@ydcrh08 utility]$ . oraenv
ORACLE_SID = [yictldt10g] ?
The Oracle base for ORACLE_HOME=/opt/oracle/product/10.2.0.4.0.a is /opt/oracle/product
Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.
[oracle@ydcrh08 utility]$  sqlplus /nolog
SQL*Plus: Release 10.2.0.4.0 - Production on Thu Apr 7 14:59:19 2011
Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.
SQL> connect / as sysdba
Connected to an idle instance.
SQL> connect / as sysdba
Connected to an idle instance.
SQL> startup
ORACLE instance started.

Total System Global Area 4060086272 bytes
Fixed Size                  2088984 bytes
Variable Size            1358958568 bytes
Database Buffers         2684354560 bytes
Redo Buffers               14684160 bytes
Database mounted.
ORA-01092: ORACLE instance terminated. Disconnection forced

[oracle@ydcrh08 udump]$ pwd
/db/yictldt10g/dbdump/udump
[oracle@ydcrh08 udump]$ ls -l
total 8
-rw-rw---- 1 oracle oracle  639 Apr  7 15:05 yictldt10g_ora_13893.trc
-rw-rw-r-- 1 oracle oracle 2158 Apr  7 15:06 yictldt10g_ora_13923.trc
[oracle@ydcrh08 udump]$ cat yictldt10g_ora_13923.trc
Dump file /db/yictldt10g/dbdump/udump/yictldt10g_ora_13923.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
ORACLE_HOME = /opt/oracle/product/10.2.0.4.0.a
System name:    Linux
Node name:      ydcrh08
Release:        2.6.18-164.el5xen
Version:        #1 SMP Tue Aug 18 15:59:52 EDT 2009
Machine:        x86_64
Instance name: yictldt10g
Redo thread mounted by this instance: 1
Oracle process number: 16
Unix process pid: 13923, image: oracle@ydcrh08 (TNS V1-V3)

*** ACTION NAME:() 2011-04-07 15:06:01.333
*** MODULE NAME:(sqlplus@ydcrh08 (TNS V1-V3)) 2011-04-07 15:06:01.333
*** SERVICE NAME:() 2011-04-07 15:06:01.333
*** SESSION ID:(652.3) 2011-04-07 15:06:01.333
Thread 1 checkpoint: logseq 167, block 2, scn 2130297
    on-disk rba: logseq 164, block 61806, scn 2070286
  start recovery at logseq 167, block 2, scn 2130297
*** 2011-04-07 15:06:01.960
Started resilvering redo thread 1 seq 167: blocks 2-2
*** 2011-04-07 15:06:02.071
Completed resilvering redo thread 1 seq 167
----- Redo read statistics for thread 1 -----
Read rate (SYNC): 0Kb in 0.83s => 0.00 Mb/sec
Total physical reads: 8192Kb
Longest record: 0Kb, moves: 0/1 (0%)
Longest LWN: 0Kb, moves: 0/1 (0%), moved: 0Mb
Last redo scn: 0x0000.0020817a (2130298)
----------------------------------------------
----- Recovery Hash Table Statistics ---------
Hash table buckets = 65536
Longest hash chain = 0
Average hash chain = 0/0 = 0.0
Max compares per lookup = 0
Avg compares per lookup = 0/0 = 0.0
----------------------------------------------
*** 2011-04-07 15:06:02.203
KCRA: start recovery claims for 0 data blocks
*** 2011-04-07 15:06:02.203
KCRA: blocks processed = 0/0, claimed = 0, eliminated = 0
*** 2011-04-07 15:06:02.208
Recovery of Online Redo Log: Thread 1 Group 3 Seq 167 Reading mem 0
----- Recovery Hash Table Statistics ---------
Hash table buckets = 65536
Longest hash chain = 0
Average hash chain = 0/0 = 0.0
Max compares per lookup = 0
Avg compares per lookup = 0/0 = 0.0
----------------------------------------------
ORA-30012: undo tablespace 'UNDOTBS1' does not exist or of wrong type

check pfile, changed as undo_tablespace=undorbs