This thread didn't get any responses after a couple of days, so I posted this same thread in the "9.3 Testing" forum and received a couple of responses: one from someone asking for more info, and another from someone saying they didn't have a similar problem with 9.3 and their ESXi setup. I didn't have time to look into the issue and respond further until now, and I can't find that thread anymore--it seems to have been deleted along with the "9.3 Testing" forum.
So.. now some more details:
I'm fairly new to iSCSI and ESXi, and started playing with it in 9.2.1.8. I was following a video tutorial, which I can't seem to find now, but it pretty much had me add a portal entry, initiator entry, and targets and extents, and associated them together using default values for the most part. The only thing I recall that wasn't quite default was having to enable a box under the first tab, per the video tutorial, which was probably "Enable LUC". I tested different VMs with datastores provided by NFS and iSCSI file and block extents. I also tested that the VMs came back up after rebooting the ESXi box. Everything was working fine..
Before I upgraded to 9.3, I whittled down to one iSCSI file-based extent/target and one VM to simplify things. I remember when I upgraded from 9.2 to 9.3, a couple of the entries in the iSCSI tabs were missing and had to be re-created. I don't recall exactly which tabs, but it was pretty much: click on "Add _____", accept defaults, click "OK" to replace the missing entries, and iSCSI on 9.3 was working again.
However, now whenever I reboot my ESXi box, the single VM on it doesn't start up and shows up as "Unknown". The datastore used by the VM (provided by that iSCSI target) needs to be re-added in vSphere Client under the host's Configuration tab > Hardware / Storage > Add Storage > Disk/LUN, where it spends a few seconds scanning for the target. Once that's done, the VM shows up and I can power it on again. How do I avoid having to do this with every reboot ?
I know the iSCSI service is provided by different software between 9.2 and 9.3. I can't find a corresponding "Enable LUC" option in 9.3, perhaps that has something to do with it ?