ORA-19573: cannot obtain exclusive enqueue for datafile 8

$ ./rman target / nocatalog

Recovery Manager: Release 10.2.0.4.0 - Production on Sun Oct 06 13:55:43 2013

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

connected to target database: SSAERP (DBID=3389811866, not open)
using target database control file instead of recovery catalog

RMAN>  RECOVER DATABASE NOREDO;

Starting recover at 06-Oct-13
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: sid=1982 devtype=SBT_TAPE
channel ORA_SBT_TAPE_1: Veritas NetBackup for Oracle - Release 6.5 (2007072323)
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=982 devtype=DISK
channel ORA_DISK_1: starting incremental datafile backupset restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
destination for restore of datafile 00008: /ora_dat/drssaerp/xdb_SSAERP02.dbf
destination for restore of datafile 00019: /ora_idx/drssaerp/idb_SSAERP02.dbf
channel ORA_DISK_1: reading from backup piece /ora_idx/drssaerp/bk/forstandby_l ptes4o_1_1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of recover command at 06/10/2013 13:57:11
ORA-19870: error reading backup piece /ora_idx/drssaerp/bk/forstandby_lvptes4o_1 _1
ORA-19573: cannot obtain exclusive enqueue for datafile 8


Solution:

It seems database is open mode for which performing restore
Shutdown database and put the mount stage and start recovery.

Restore Database from Incremental Backup

$ ./rman target / nocatalog

Recovery Manager: Release 10.2.0.4.0 - Production on Sun Jan 25 10:43:52 2015

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

connected to target database: SSAERP (DBID=3389811866, not open)
using target database control file instead of recovery catalog

RMAN> catalog start with '/ora_idx/drssaerp/bk';

searching for all files that match the pattern /ora_idx/drssaerp/bk

List of Files Unknown to the Database
=====================================
File Name: /ora_idx/drssaerp/bk/forstandby_lvptes4o_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m0ptesea_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m1ptesnr_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m2ptet1n_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m3ptetb8_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m4ptetl3_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m5ptetuv_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m6pteu8q_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m7pteuja_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m8pteuun_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m9ptevap_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_maptevo3_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mbptf028_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mcptf0b6_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mdptf0ir_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_meptf0me_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mfptf0q2_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_lupterr7_1_1

Do you really want to catalog the above files (enter YES or NO)? yes
cataloging files...
cataloging done

List of Cataloged Files
=======================
File Name: /ora_idx/drssaerp/bk/forstandby_lvptes4o_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m0ptesea_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m1ptesnr_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m2ptet1n_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m3ptetb8_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m4ptetl3_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m5ptetuv_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m6pteu8q_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m7pteuja_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m8pteuun_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_m9ptevap_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_maptevo3_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mbptf028_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mcptf0b6_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mdptf0ir_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_meptf0me_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_mfptf0q2_1_1
File Name: /ora_idx/drssaerp/bk/forstandby_lupterr7_1_1

RMAN>