Make sense of iSCSI.

Start here

iSCSI hands a client a raw disk instead of a share, and almost every problem people hit with it comes from that one difference. These four pages cover it in the order the questions usually arrive.

The guides cover iSCSI SAN targets, MPIO multipathing and LUN provisioning. Begin with the ownership model, choose the protocol your application needs, then follow the target and client configuration for your platform. For an existing connection problem, start with the troubleshooting guide and the message your initiator reports.

1. 1 · Understand it
   What is an iSCSI LUN?

   What an IQN identifies, what a LUN really is, and why MPIO and link aggregation are not the same mechanism.

2. 2 · Decide
   iSCSI vs NFS vs SMB

   Block or file, and what changes with it: locking, path redundancy, authentication and how each one behaves when the storage disappears.

3. 3 · Build it
   iSCSI target setup on Unraid, TrueNAS and Synology

   Unraid plugin and pool placement, TrueNAS zvol mappings, Synology SAN Manager, and connecting Proxmox as an initiator.

4. 4 · Fix it
   Login, timeout and path errors

   Portal, discovery, login, ACL, CHAP, MTU, then the timers that decide when a dead path becomes a filesystem error.