illumos gate

When support for the namespace EUI64 was added in #7382, it seemed like a good idea to expose that to userspace in such a way that it replaced the namespace ID as a means for specifying a namespace:

# nvmeadm list nvme1/1413577160000a35
nvme1: model: ATP NVMe M.2 2280 SSD, serial: 20040276-000142, FW rev: 42A0S79A, NVMe v1.3
  nvme1/1413577160000a35 (c3t1413577160000A35d0): Size = 488386 MB, Capacity = 488386 MB, Used = 101603 MB

This will create two problems. First, once we'll be using the full NGUID, the size of the namespace identifier doubles to a full 32 characters, and so does device node name. This will make the output of 'nvmeadm list' even wider than it already is, causing ugly line breaks even on wide terminals, only to display the same information twice.

And second, once we have namespace management we'll run into usability nightmare. Just detaching a controller from a namespace will make the EUI64 or NGUID invisible to the driver, and deleting and re-creating a namespace may change the EUI64 or NGUID completely. This means that across these operations, the namespace identifier may change, the device nodes may have to be deleted and recreated by the driver, and the user will be needlessly confused.

Returning to the old original behaviour of always using the namespace nsid will avoid all of this, as the nsid will be a small number in most use cases that will never change across namespace management operations:

# nvmeadm list nvme1/1
nvme1: model: ATP NVMe M.2 2280 SSD, serial: 20040276-000142, FW rev: 42A0S79A, NVMe v1.3
  nvme1/1 (c3t6141357160000A351413570000000000d0): Size = 488386 MB, Capacity = 488386 MB, Used = 101451 MB