That’s good news — what you’re seeing now is the expected state.

A quick clarification first:

Power cycle means exactly what you did: shut the machine down completely and turn it back on. There is no command involved. You did the right thing.

Regarding the current status:

The drive showing up in Disks but marked as unknown is normal

At this point the disk has:

No partition table

No filesystem

“Unknown” here does not indicate a problem, only that nothing has been created on it yet

About sg_readcap:

sg_readcap -l is correct

There is no direct “comparison” mode; running it separately on sda and sdb is exactly what was intended

The important thing is that both drives now report sane, consistent values (logical block size, capacity, no protection enabled)

Next steps:

Yes, the next step is normal disk setup, just like with any new drive:

1. Create a partition table (GPT is typical)

2. Create one or more partitions

3. Create a filesystem (or add it back into ZFS if that’s your goal)

At this stage the drive has transitioned from “unusable” to functionally recovered. From here on, you’re no longer fixing a problem — you’re just provisioning storage.

If you plan to put it back into TrueNAS/ZFS, it’s usually best to let TrueNAS handle partitioning and formatting itself rather than doing it manually on Linux.

Nice work sticking with the process and verifying things step by step.