Re: devfs
Richard Gooch (rgooch@atnf.CSIRO.AU)
Sun, 11 Jan 1998 21:51:34 +1100
Michael Neuffer writes:
> On Sun, 11 Jan 1998, Richard Gooch wrote:
> > > No not controllers. This is buses on the controller. 4 bits for this
> > > should be the lower limit. The smallest SSA that you can buy from
> > > SUN for example has already 6 buses.
> >
> > That's interesting. Since you seem to know something about SCSI host
> > adapters with multiple SCSI buses, can you please tell us how they
> > show that in /dev? I'm aware of the following format:
> >
> > cCtTdDsS
> >
> > where <C> is the controller number (host adaptor), <T> is the SCSI
> > target (SCSI ID), <D> is the device number (LUN) and <S> is the stripe
> > (partition).
> >
> > Where do they put the per-host/controller SCSI bus ID?
>
> Solaris resorts to an ugly trick to encode the buses of the SSAs.
> When speaking to an SSA the LUN gets dropped and the fields shift
> right to make room for the channel (bus).
>
> Now the meaning is follows:
>
> cCtBdTsS
>
> Where <C> is the controller, <B> is the bus/channel, <T> is the target and
> <S> is the slice.
>
> This allows then to stay compatible with their naming sheme but has the
> drawback of dropping support for LUNs. This only works properly for the
> special case of the SSAs since you only have disk drives in them.
>
> However I do not think that we should make the same mistake as them
> and cut ourselves off from supporting multi LUN devices.
Agreed! Considering this, I'm open to alternative naming schemes, but
only if they preserve the information.
Regards,
Richard....