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Oracle ASM
Using loopback devices in place of real disks
Refs:
Jeff Hunter, How to use Files in place of Real Disk Devices for ASM
Fabien Faye, Howto create Loop Device on REDHAT, CENTOS or FEDORA
For testing only
Create disk files
$ cd /exports/oracle $ mkdir asmdisks $ chown oracle:dba asmdisks $ dd if=/dev/zero of=asmdisks/_file_disk10 bs=1k count=1000000 # 1000MB $ dd if=/dev/zero of=asmdisks/_file_disk11 bs=1k count=1000000 # 1000MB $ dd if=/dev/zero of=asmdisks/_file_disk12 bs=1k count=1000000 # 1000MB $ dd if=/dev/zero of=asmdisks/_file_disk13 bs=1k count=1000000 # 1000MB $ ls -l asmdisks total 4003936 -rw-r--r-- 1 oracle oinstall 1024000000 Dec 9 07:00 _file_disk10 -rw-r--r-- 1 oracle oinstall 1024000000 Dec 9 07:00 _file_disk11 -rw-r--r-- 1 oracle oinstall 1024000000 Dec 9 07:01 _file_disk12 -rw-r--r-- 1 oracle oinstall 1024000000 Dec 9 07:01 _file_disk13
Map loopback devices to disk files
# Find first unused device # losetup -f /dev/loop0 # losetup /dev/loop0 /exports/oracle/asmdisks/_file_disk10 # losetup /dev/loop1 /exports/oracle/asmdisks/_file_disk11 # losetup /dev/loop2 /exports/oracle/asmdisks/_file_disk12 # losetup /dev/loop3 /exports/oracle/asmdisks/_file_disk13
Create raw devices
# raw /dev/raw/raw10 /dev/loop0 /dev/raw/raw10: bound to major 7, minor 0 # raw /dev/raw/raw11 /dev/loop1 /dev/raw/raw11: bound to major 7, minor 1 # raw /dev/raw/raw12 /dev/loop2 /dev/raw/raw12: bound to major 7, minor 2 # raw /dev/raw/raw13 /dev/loop3 /dev/raw/raw13: bound to major 7, minor 3 # ls /dev/raw raw1 raw10 raw11 raw12 raw13 raw2 raw3 raw4 # chown oracle:dba /dev/raw/raw10 # chown oracle:dba /dev/raw/raw11 # chown oracle:dba /dev/raw/raw12 # chown oracle:dba /dev/raw/raw13 # chmod 660 /dev/raw/raw10 # chmod 660 /dev/raw/raw11 # chmod 660 /dev/raw/raw12 # chmod 660 /dev/raw/raw13
Check visibility of raw devices in ASM
SQL> l
1* select group_number, disk_number, mount_status, header_status, state, path from v$asm_disk
SQL> /
GROUP_NUMBER DISK_NUMBER MOUNT_S HEADER_STATU STATE PATH
------------ ----------- ------- ------------ -------- ---------------
0 0 CLOSED CANDIDATE NORMAL /dev/raw/raw13
0 1 CLOSED CANDIDATE NORMAL /dev/raw/raw12
0 2 CLOSED CANDIDATE NORMAL /dev/raw/raw11
0 3 CLOSED CANDIDATE NORMAL /dev/raw/raw10
2 2 CACHED MEMBER NORMAL /dev/raw/raw4
2 1 CACHED MEMBER NORMAL /dev/raw/raw3
2 0 CACHED MEMBER NORMAL /dev/raw/raw2
1 0 CACHED MEMBER NORMAL /dev/raw/raw1
Create a diskgroup
SQL> create diskgroup LOOPDG normal redundancy failgroup fg1 disk '/dev/raw/raw10', '/dev/raw/raw12' failgroup fg2 disk '/dev/raw/raw11', '/dev/raw/raw13'; Diskgroup created.
Check diskgroup
SQL> select group_number, name, total_mb, free_mb, state, type from v$asm_diskgroup;
GROUP_NUMBER NAME TOTAL_MB FREE_MB STATE TYPE
------------ ------------------------------ ---------- ---------- ----------- ------
1 DG1 8189 7183 MOUNTED EXTERN
2 DG2 786414 322583 MOUNTED EXTERN
3 LOOPDG 3904 3798 MOUNTED NORMAL
SQL> select group_number, disk_number, mount_status, header_status, state, path, failgroup from v$asm_disk;
GROUP_NUMBER DISK_NUMBER MOUNT_S HEADER_STATU STATE PATH FAILGROUP
------------ ----------- ------- ------------ -------- --------------- ------------------------------
2 2 CACHED MEMBER NORMAL /dev/raw/raw4 DG2_0002
2 1 CACHED MEMBER NORMAL /dev/raw/raw3 DG2_0001
2 0 CACHED MEMBER NORMAL /dev/raw/raw2 DG2_0000
1 0 CACHED MEMBER NORMAL /dev/raw/raw1 DG1_0000
3 3 CACHED MEMBER NORMAL /dev/raw/raw13 FG2
3 1 CACHED MEMBER NORMAL /dev/raw/raw12 FG1
3 2 CACHED MEMBER NORMAL /dev/raw/raw11 FG2
3 0 CACHED MEMBER NORMAL /dev/raw/raw10 FG1
Create database objects using new diskgroup
SQL> alter session set db_create_file_dest='+LOOPDG';
Session altered.
SQL> create tablespace LOOPTS datafile size 500M autoextend on next 100M maxsize 2000M;
Tablespace created.
SQL> select file_name from dba_data_files where tablespace_name='LOOPTS';
FILE_NAME
--------------------------------------------------------------------------------
+LOOPDG/nasa/datafile/loopts.256.705137387
SQL> create table LOOPTAB tablespace LOOPTS as select * from dba_source;
Table created.
SQL> select count(*) from looptab;
COUNT(*)
----------
295139
Use asmcmd to view datafile in ASM
ASMCMD [+] > ls -l State Type Rebal Unbal Name MOUNTED EXTERN N N DG1/ MOUNTED EXTERN N N DG2/ MOUNTED NORMAL N N LOOPDG/ ASMCMD [+] > cd loopdg/nasa/datafile ASMCMD [+loopdg/nasa/datafile] > ls -l Type Redund Striped Time Sys Name DATAFILE MIRROR COARSE DEC 09 07:00:00 Y LOOPTS.256.705137387
Remote connection to ASM instance
If you attempt a remote connection to ASM and you see an error similar to:
Enter user-name: sys/pwd@asm as sysdba ERROR: ORA-12154: TNS:could not resolve the connect identifier specified
then define a connect string in tnsnames.ora similar to:
ASM =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = hostname_or_IP_address)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = +ASM)
(INSTANCE_NAME = +ASM)
# Allow connect to blocked ASM instance
(UR = A)
)
)
If you see an error similar to:
Enter user-name: sys/pwd@asm as sysdba ERROR: ORA-12528: TNS:listener: all appropriate instances are blocking new connections
then you need to add UR = A to your connect string in tnsnames.ora (see example above).
This will allow connection to the normally blocked ASM instance.
If you see an error similar to:
Enter user-name: sys/pwd@asm as sysdba ERROR: ORA-01017: invalid username/password; logon denied
then either:
a) you really did get the password wrong,
b) remote_login_passwordfile not set to EXCLUSIVE, this can be fixed by running:
SQL> alter system set remote_login_passwordfile=EXCLUSIVE scope=spfile; System altered.
and restartig ASM and all dependent instances.
or c) the password file doesn't allow the connection, recreate the password file:
$ orapwd file=orapw+ASM password=pwd entries=5 force=y
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