when to use "/dev/nvme0ns1"

[Warner Losh]

On Sat, Dec 5, 2020 at 10:36 PM Yuri Pankov <yuripv at yuripv.dev> wrote:

> Krishnamraju Eraparaju wrote:
> > Hi All,
> >
> >
> > I see there are two ways of accessing NVMe disk:
> >     1)GEOM based: /dev/nvd0 or /dev/nda0
> >     2)/dev/nvme0ns1
> >
> > When should one use " /dev/nvme0ns1"?
>
> See nvmecontrol(8) for the commands that operate on namespace ids.  And
> while you could still use nvd/nda devices for those, specifying the
> namespace explicitly could be helpful.
>
> An excerpt from man page:
>
> DEVICE NAMES
>       Where ⟨namespace-id⟩ is required, you can use either the nvmeXnsY
>       device, or the disk device such as ndaZ or nvdZ.  The leading /dev/
>       is omitted.
>

Yes. nvd* and nda* are block devices. nvme0ns1 is for administrative things
when you may or may not have an nda/nvd device hanging around, or you want
to deal with a specific thing and don't know the mapping to the nda/nvd
device.

Warner