7. iSCSI and Multipathing

Outcome

Build and diagnose a redundant iSCSI path without confusing IP reachability, target discovery, authenticated session and usable multipath state.

Level: Practitioner · Time: 50 minutes · Prerequisite: SAN Architecture

Learn

NIC/VLAN/IP/MTU
→ target portal reachability
→ discovery
→ CHAP authentication
→ iSCSI session
→ LUN mapping
→ SCSI device
→ multipath grouping and policy

Each layer can succeed while the next fails. A ping does not prove discovery; discovery does not prove login; login does not prove LUN authorization; multiple devices do not prove correct multipath grouping.

Practice

Use the Academy’s iSCSI terminal to create a portal, target and LUN mapping, discover it, authenticate, establish sessions and validate multipathing. Trigger path loss and CHAP incidents and recover them.

Check your understanding

What evidence separates a network problem from an authentication problem?
Why can two visible SCSI devices represent one LUN?
Which settings must match end to end before changing jumbo-frame MTU?

Production boundary

Commands vary across initiator, target and operating-system implementations. Validate timeout, replacement-timeout, path-checker and queueing behavior for the deployed stack.

Next step

Continue to Operations and Incident Response.