What device path do you have to specify in ASM, if you want to use the multipath device?
/dev/sdc/ = first path
/dev/sdd = second path
/dev/multipatha = path of the multipath OS driver
A.
Only /dev/sdc is enough, because asmlib knows it is a multipath device.
B.
/dev/sdc as disk group and /dev/sdd as failure group.
C.
You need to specify all the three devices and only then ASM will know this is a multipath device.
D.
Only /dev/multipatha is enough.
Explanation:
eference: http://www.oracle.com/technetwork/topics/linux/asmlib/multipath-097959.html
Agree D >>>>
There are “”two”” issues with using multipath disks in ASM.
Issue: 1>>>>
ASM cannot handle seeing the same disk twice. If it does, it will cause an error. A single disk can appear three times in a multipath configuration:
The first path to the disk
The second path to the disk
The multipath access point
Here’s an example: say a system has one local disk, /dev/sda, and one disk attached via external storage. The machine has two connections, or paths, to that external storage. The Linux SCSI driver will see both paths. They will appear as /dev/sdb and /dev/sdc. The system may access sdb or sdc, the access ends up in the same place.
If multipathing is enabled, there will be a multipath disk, for example /dev/multipatha, that can access both paths. That is, any I/O to multipatha can use either path. If a system were using the sdb path, and that cable is unplugged, the system will get an error. But the multipath disk will know to switch to the sdc path.
Issue: 2>>>
Here is the second issue: which path does ASM see ?
ASM only sees one path –
In its default configuration, ASMLib will choose the first path it finds. This is the first path as reported by Linux. Depending on your storage driver, it could be the multipath, or it could be one of the single paths.