Messages in this thread | | | Date | Wed, 14 Jan 1998 17:16:56 -0800 | From | "Leonard N. Zubkoff" <> | Subject | Re: devfs |
| |
From: Bob Tracy <rct@gherkin.sa.wlk.com> Date: Wed, 14 Jan 1998 07:29:40 -0600 (CST)
Time to lay it to rest, but here's a way for folks to live with 'd' and 's'. Think 'd == device, s == subdevice' and assign whatever meaning is consistent for a particular type of device. In the System III/V way of naming things, 'd' was never intended to represent 'disk'. The original meaning of 's' is a bit more obscure, and 'slice' was at least as common an interpretation as 'subdevice' as I remember it. Regardless, 'stripe' or 'strip' wasn't one of the valid meanings. In my mind at least, there's a natural correlation between a subdevice and a partition, and 's' isn't as limited as 'p' if/when you want to apply the naming scheme to a device that doesn't have partitions.
An example: for SCSI devices, '(d)evice == LUN'.
One more example: ESDI disks. On the old 3B2 computers with ESDI disks, a SCSI target ID (t1-t7, t0 was reserved for the host adapter) corresponded to a SCSI <--> ESDI controller (Everex) that could support up to four spindles (d0-d3). Simple math implies you could hang up to 28 spindles off a single SCSI host adapter if you were crazy enough to put up with the I/O bottleneck.
The ESDI example in particular is why I would prefer 'd' to 'u', but I can live with 'u' if that's the consensus.
The device/subdevice explanation makes a great deal of sense, and would allow extending the naming consistently to non-SCSI devices where the use of logical unit and slice isn't appropriate. If it's not yet too late, I think this is a good argument for using "d" and "s".
Leonard
| |