Oracle introduced ASM Filter Driver in Oracle Database 12c (184.108.40.206). The ASM Filter Driver replaces the functionality of ASMLib, and adds new functionality including the ability to protect ASM devices from I/Os that do not originate from the Oracle stack.
Oracle has stated that future versions of ASM Filter Driver will include support for TRIM on thinly provisioned disks, allowing deleted blocks to be released back to the pool for reuse.
New devices can be stamped as ASM disks as follows:
[root@oel6solo ~]# asmcmd afd_label DATA1 /dev/sdb
In the example above we have stamped the device /dev/sdb as the ASM disk DATA1.
With ASM Filter Driver, the DBA will see devices named AFD:diskname.
[oracle@oel6solo asm]$ asmcmd lsdsk --statistics
Reads Write Read_Errs Write_Errs Read_time Write_Time Bytes_Read Bytes_Written Voting_File Path
1374 488 0 0 .624 .455 18339328 2746880 N AFD:DATA1
2213 80 0 0 .776 .098 30583808 1172992 N AFD:DATA2
1780 333 0 0 .746 .305 34169344 4833280 N AFD:DATA3
1576 111 0 0 .682 .107 29904896 904704 N AFD:DATA4
The ASM instance parameter ASM_DISKSTRING should be set to “AFD:*” when using ASM Filter Driver.
[oracle@oel6solo asm]$ srvctl config asm
ASM home: <CRS home>
Password file: +DATA/orapwasm
ASM listener: LISTENER
ASM diskgroup discovery string: AFD:*