CFWorx

iSCSI

· in Intro to SAN and NAS Storage (Neil Anderson)

What it is

Internet Small Computer System Interface: SCSI commands over TCP/IP on ordinary Ethernet.

Historically the budget alternative to Fibre Channel: more packet overhead and a lower-reliability reputation, but mature and very popular.

The network options: share the data network, run a dedicated storage network, or share switches with separate storage and data VLANs. TOE (TCP Offload Engine) cards, aka iSCSI HBAs, offload the TCP/IP grind from the server CPU.

Addressing

No WWNs here. Hosts get an IQN (iSCSI Qualified Name), up to 255 chars: iqn.yyyy-mm.naming-authority:unique-name, like iqn.1991-05.com.microsoft:testHost. (EUI is the rare alternative.)

The IQN is per host, like a WWNN. Individual ports are addressed by plain IP.

There’s no FLOGI/PLOGI/PRLI equivalent: the admin points the initiator at one IP in the target portal group, and it discovers the target IQN and remaining ports from there. Multipathing then picks paths, same as FC; the intelligence still lives on the client.

Security

LUN masking works as in FC, keyed on IQN instead of WWPN.

There’s no zoning in iSCSI. Instead: password authentication between initiator and target against spoofing, and optional end-to-end IPsec.

Array-side config

The same redundant pattern as the NAS protocols: dedicated ports (e0d 172.23.3.120, e0e .121) across two switches.

Adapter cheat sheet

Stack comparison