An I/O path generally consists of an initiator port, fabric port, target port, and LUN. Multi-pathing software requires all the required disks to be visible on each available and eligible HBA. These multi-paths will be detected by probing the World Wide Device Identifiers (WWD ID).

Benefits:
— Storage is visible with multi-paths to storage, but still it’s presented as same single disk.
— This is useful in case of failures that makes disk not accessible. The multi-path storage fail-over to other path.
— Software also provide auto-failback capabilities.

Oracle ASM can be configured on these devices, because these disks are still presented to asm as single device disks. So we can deploy ASM using these disks without issues.

Benefits:
— In case of failures, the disk is immediately present to ASM using alternative storage.
— ASM has other benefits like striping and mirroring. so in case of complete disk failure, it uses mirrored copies and rebalance data with available disks.

Monitoring multipath disks:
$iscsiadm list target -S  — Know configuration
$cat /etc/iscsi/iscsid.conf — configuration file, iscsid and iscsiadm on startup.
$cat /var/lib/iscsi/nodes –nodes with their targets.

MPxIO in solaris provide multipath solutions for storage servers:
Oracle Solaris SAN configuration and Multipathing:  https://docs.oracle.com/cd/E26502_01/html/E29008/