On Thu, 22 Mar 2007, David Betz wrote: 0 is the drive and a is the partition. However, bear in mind that (this being Unix) the *real* magic is done in the directory entry. If you take a close look, you'll see that /dev/ra0a is a block special device with two parts: the device number (index into the devsw[] array) and unit number. You can create a special file with *any* name that maps to the same device as /dev/ra0a. -- roger ivie rivie at ridgenet.net

Then that seems like a reasonable inference, yes. :-) Or rather, it is one of the partitions on that disk. ra0a is just one of the (probably) eight possible partitions on ra0. On some systems, the partition table was compiled in; on others, it was read off the disk. I don't know which Ultrix 4.3 was. It would be ra1; the partitios on it would be /dev/ra1a through /dev/ra1h. (As far as I can recall, Ultrix did not have any /dev/ entries for the disks in their own right, only for the partitions on them. In this respect it was like most other Unices of the time.) Good guess, but not quite. "ra" is the device type, or, more precisely, the name of the driver responsible for it. "0" indicates that it's the first "ra" device (these things are normally numbered starting from 0). "a" indicates that you're dealing with partition #1 (partitions are normally named with letters, a thorugh h in most cases in that era). You may note this device name does not include any part specifying what controller ra0 is attached to. This is normal; Unix device probing then (and in many systems now as well) hides the path through which a device is attached to the system, exposing only the end result - the device itself. I don't know; I'm not familiar with Ultrix naming conventions for CD drives. Probably ra1 or cd0 or some such. This is another issue entirely; the naming used by the ROMs does not bear much relation to the names used by Ultrix. I also don't know that SCSI controller; it might or might not be bootable, and if not, there is no name you can use to boot from it. It probably needs to speak MSCP to be bootable, though it's been too long for me to remember the ROM naming scheme for MSCP devices. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse at rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

On 3/22/07, David Betz <dbetz at xlisper.com> wrote: With BSDish nomenclature, the 'ra' is the radriver (MSCP), the digit is the drive unit number, and the letter is the partition. The first partition is 'a', and for a booted disk, it'll be '/'. The second partition is 'b', commonly the swap partition, 'c' is the whole disk, and other letters have other traditional uses, but they aren't set in stone. http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/disk-organization… If I'm remembering correctly, we used to arrange Ultrix/BSDish machines like... ra0a - / ra0b - swap ra0d - /usr ra0g - /usr/users (before home dirs started appearing in /home). If you started adding other drives, you might mount /usr/users on its own drive (ra1c, say, for the entire disk), then use ra0g or a combination of ra0e and ra0f for /tmp or /var or /var/spool, to help lower the risk of unpriv'ed processes from filling up /, which is a very, very bad thing. Hmm... I never used a CD-ROM under Ultrix, so I can't be sure what slice you'd use (if any), but if the CD-ROM is on a different controller than the boot drive, the second letter should get bumped up, so if you booted ra0a, the CD-ROM drive might be rb0, but I suppose it depends. I also have limited experience with multiple drive controllers in the same box - we had small installations with typically one large drive controller (MSCP or ESDI or RK611), and probably one small drive controller (RL11), some number of communications ports, sync and async, and that's about it. ISTR there are multiple ways of building device names under BSDish flavors of UNIX, so my memories of Ultrix might be fuzzing over into memories of 4BSD and SunOS, if there are any variations. System V, like Solaris 2, uses a clearer scheme c0t0d0s0 for "controller 0, target (like SCSI address) 0, disk (like SCSI LUN) 0, slice (partition) 0". Back when Solaris 1 (SunOS) was being eclipsed by Solaris 2.0, I remember some grumbling about how verbose the scheme is, but on the bright side, it requires less deep understanding to read than "ra0d" vs "rc3g", etc. -ethan