SQL> startup force nomount
ASM instance started

Total System Global Area   83886080 bytes
Fixed Size                  1217836 bytes
Variable Size              57502420 bytes
ASM Cache                  25165824 bytes
SQL> create diskgroup dgroup1 normal redundancy
  2  failgroup cont1 disk
  3  '/dev/oracleasm/disks/VOL1',
  4  '/dev/oracleasm/disks/VOL2',
  5  failgroup cont2 disk
  6  '/dev/oracleasm/disks/VOL3';
failgroup cont2 disk
*
ERROR at line 5:
ORA-15106: missing or invalid operating system disk locator string

SQL>
SQL> ! oerr ora 15106
15106, 00000, "missing or invalid operating system disk locator string"
// *Cause:  The command did not specify a valid operating system path
//          for the device as a string.
// *Action: Specify a valid operating system path for the device.
//

SQL> select * from v$version where rownum = 1;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod

SQL> ! uname -r
2.6.9-42.0.0.0.1.ELhugemem

====

[oracle@localhost disks]$ pwd
/dev/oracleasm/disks
[oracle@localhost disks]$ ls -lrt
total 0
brwxrwxr-x  1 oracle oinstall 253, 0 Mar 22 17:07 VOL1
brwxrwxr-x  1 oracle oinstall   8, 2 Mar 22 18:36 VOL2
brwxrwxr-x  1 oracle oinstall   8, 1 Mar 22 18:36 VOL3

create diskgroup dgroup1 normal redundancy
failgroup cont1 disk '/dev/oracleasm/disks/VOL1', '/dev/oracleasm/disks/VOL2'
failgroup cont2 disk '/dev/oracleasm/disks/VOL3';

  1  create diskgroup dgroup1 normal redundancy
  2  failgroup cont1 disk '/dev/oracleasm/disks/VOL1','/dev/oracleasm/disks/VOL2'
  3* failgroup cont2 disk '/dev/oracleasm/disks/VOL3'
SQL> /

Message from syslogd@localhost at Mon Mar 23 00:07:01 2009 ...
localhost kernel: journal commit I/O error

Diskgroup created.