Synchronizing or dead?

Was the NV+ turned off when you did the firmware upgrade? If you want to remove and then re-insert a disk (with no changes to the data at all), that is the best way.

Since you can access the NAS you might check the disk health stats.

Assuming the discrepancy doesn't clear (or that the resync never completes) - If you have disks on the HCL, you might want to open an on-line support ticket.

Yes, the NV+ was turned off and I pulled the disk out and put it in my PC and did the F/W update and SMART tests etc. using Seagates utility.
I the reinserted it into the NV+ and started it.

The NV+ then said 'Kernel panic' so I turned it off, pulled the disk out and started the NV+ again. It started without problems.

I then inserted the disk (while the NV+ was on) and it then started syncing.

The health status shown in RAIDar and Frontview for the upgraded disk is 'dead' and while the upgraded disk is in I have a hard time accessing the data on the volume. When the disk was out, I could save the most important stuff I had on it (14 years of programming projects - pwheew).

Yeah, the disks are all on the HCL. I bought it with two disks already installed and I then bought two just like them. Unfortunately, the firmware has since (in 2011 I think) been confirmed flawed by Seagate.

Could the NV+ be confused by the data already on the upgraded disk (even though it *was* in sync when I did the upgrade)? Should I format it somehow?

I had another Seagate disk (not the same model) that I did a SATA reset on to clean it, but that fried it completely. I can't see it when it's attached to my PC in neither BIOS nor via Seagates own utility (that I used to fry it). I don't think I dare to try that on another disk. :-/

Br,
Ted

Since you inserted the disk when the NV+ was running, it needs to do a resync - it has to assume that the data is stale.

I would let it sync, and submit an on-line support request.

I have cleaned disks by connecting them to my PC and deleting the partitions. That is better than formatting (as the NAS will have to reformat again anyway).

The first time I inserted the disk, the NV+ was turned off. NV+ off, disk out, upgraded F/W, inserted disk, NV+ on. Kernel panic.

The sync went on forever (30+ hours) and RAIDar couldn't find it anymore. I pulled the disk out and it the front panel still said it was syncing... The power button didn't have any effect so I pulled the cord. Reinserted the disk, powered it up, kernel panic. Cord out, disk out, power on, works again. Sigh...