Device's "stolen" sector

[Warner Losh]

On Tue, Jul 16, 2019 at 11:05 AM Wojciech Puchar <wojtek at puchar.net> wrote:

>
>
> On Tue, 16 Jul 2019, Domagoj Smolčić wrote:
>
> > 11.2-RELEASE-p9
> >
> > Tested with >1 disks:
> > --
> > SATA disk connected directly with SATA cable to MBO, shows correct
> amount of sectors.
> >    diskinfo -v ada1
> >
> > When I connect it to the same MBO over USB to SATA adapter, 1 sector is
> missing (the last one)
> >    diskinfo -v da0
> >
> > Having last sector inaccessible is a huge problem as many "things" use
> it for a metadata.
> > This has many times caused MBR disks occasionally to not be visible at
> all while being 'da0' (gpart: No such geom: da0.)
> > And also GPT disks to be in a [CORRUPT] state upon reattach directly to
> SATA interface.
> >
> > Before submitting a bug, there is only 1 variable left that I can't
> test, because I have only 1 USB to SATA adapter.
> > It might be a hardware issue, so can someone else test this too?
> >
> i have two external disk chassis with USB-SATA bridge, works just fine
>
> recently connected through it disk that was geli encrypted when directly
> connected to server. geli worked so all is fine as geli header is in last
> sector
>

It all depends... There's huge variation in the quality of USB-SATA
bridges. Some get in the way and do things like round off the last sector
when the reported capacity is odd, for example. Which is why I'm trying to
see if there's an issue with that, or if the issue is something in the da
driver. For drives with an even number of sectors, there's likely no issues
at all...

Warner