Environment:
- Oracle Linux (6.x or 7.x)
- Oracle 11g (RAC or STANDALONE)
Symptoms:
- Oracle asm fails when multipath active path has changed or redundant path change
Diagnose:
[root@oraclenode ~]$ ls -l /dev/oracleasm/disks
total 0
brw-rw---- 1 oracle dba 8, 17 May 16 15:10 DATA01
brw-rw---- 1 oracle dba 8, 33 May 16 15:10 DATA02
brw-rw---- 1 oracle dba 8, 49 May 16 15:10 DATA03
brw-rw---- 1 oracle dba 8, 65 May 16 15:10 DATA04
brw-rw---- 1 oracle dba 8, 81 May 16 15:10 DATA05
Here you can notice that device ids are 8 XX values. Validate with /dev values
brw-rw---- 1 root disk 8, 17 Feb 9 11:39 sdb1
brw-rw---- 1 root disk 8, 33 Feb 9 11:39 sdc1
brw-rw---- 1 root disk 8, 49 Feb 9 11:39 sdd1
brw-rw---- 1 root disk 8, 65 Feb 9 11:39 sde1
brw-rw---- 1 root disk 8, 81 Feb 9 11:39 sdf1
This configuration arises asm failure any time multipath connection path has changed. Becase DATA01 asm disk is connected with sdb1 path which is not valid anymore. With multipath configuration it is expected to run without any interruption.
Solution:
Configure oracle asm that is connected with multipath mappings. If this is RAC environment, perform operation on each node. Also reboot is required to make changes applied.
[root@oraclenode ~]$ oracleasm configure -I
Configuring the Oracle ASM library driver.
This will configure the on-boot properties of the Oracle ASM library
driver. The following questions will determine whether the driver is
loaded on boot and what permissions it will have. The current values
will be shown in brackets ('[]'). Hitting without typing an
answer will keep that current value. Ctrl-C will abort.
Default user to own the driver interface [oracle]:
Default group to own the driver interface [dba]:
Start Oracle ASM library driver on boot (y/n) [y]:
Scan for Oracle ASM disks on boot (y/n) [y]:
The next two configuration options take substrings to match device names.
The substring "sd" (without the quotes), for example, matches "sda", "sdb",
etc. You may enter more than one substring pattern, separated by spaces.
The special string "none" (again, without the quotes) will clear the value.
Device order to scan for ASM disks []:
Devices to exclude from scanning []: sd
Directories to scan [ ]: /dev/mapper/
Use device logical block size for ASM (y/n) [y]:
Writing Oracle ASM library driver configuration: done
Required changes are: exclude deviced started with sd from scanning and add /dev/mapper directory to scan.
[oracle@tarsusdhdbnode1 ~]$ ls -l /dev/oracleasm/disks/
toplam 0
brw-rw---- 1 oracle dba 252, 11 May 16 15:25 DATA01
brw-rw---- 1 oracle dba 252, 8 May 16 15:25 DATA02
brw-rw---- 1 oracle dba 252, 9 May 16 15:25 DATA03
brw-rw---- 1 oracle dba 252, 10 May 16 15:25 DATA04
brw-rw---- 1 oracle dba 252, 12 May 16 15:25 DATA05
brw-rw---- 1 root disk 252, 11 Mar 9 03:44 dm-11
brw-rw---- 1 root disk 252, 8 Mar 9 03:44 dm-8
now oracle asm disks uses device mapper disks.
Read More:
https://www.oracle.com/technetwork/server-storage/linux/multipath-097959.html
https://docs.oracle.com/en/database/oracle/oracle-database/18/cwlin/configuring-disk-scan-ordering-to-select-multipath-disks.html#GUID-AF493B94-D125-4601-8450-299E5E65AD95
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