DIFFERENCE BETWEEN ASMLIB AND ASMFILTER DRIVER
ASMLIB – It is an utility to manage oracle asm efficiently to create,delete,rename and querydisk asm diskgroup.
Example:
[root@dc01x01 oracle]# oracleasm querydisk OCRVOD1
Disk "OCRVOD1" is a valid ASM disk
[root@dc01x01 oracle]# dd if=/dev/zero of=/dev/sdg bs=1M count=10
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 0.400026 s, 26.2 MB/s
[root@dc01x01 oracle]# dd if=/dev/zero of=/dev/sdh bs=1M count=10
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 0.792787 s, 13.2 MB/s
[root@dc01x01 disks]# oracleasm querydisk OCRVOD1 OCRVOD2
Disk "OCRVOD1" defines an unmarked device
Disk "OCRVOD2" defines an unmarked device
[root@dc01x01 disks]# oracleasm scandisks
Reloading disk partitions: done
Cleaning any stale ASM disks...
Cleaning disk "OCRVOD1"
Cleaning disk "OCRVOD2"
Scanning system for ASM disks...
[root@dc01x01 disks]# oracleasm listdisks
DATAC1
DATAC2
RECOC1
RECOC2
REDO01
REDO02
[root@dc01x01 disks]# oracleasm listdisks
DATAC1
DATAC2
OCRVOD1
OCRVOD2
RECOC1
RECOC2
REDO01
REDO02
ASMFILTER DRIVER is also an utility which was introduced in 12cr2 version to manage ASM disks efficiently. It guards other external disk from accessing the ASM disks preventing corruption of the ASM disk header
Difference: ASM disk header can be modified with the help of utility like dd while using ASMLIB but in ASMFILTER DRIVER the disk doesnot allow dd utility to perform writes which makes the difference.