Re: SCSI disk devices

Perry Wagle (wagle@cse.ogi.edu)
Thu, 08 May 1997 15:57:18 -0700


What Solaris 2.5 (at least) does is to give you old style names:

seismo!wagle[108] ls -l /dev/sd3c
lrwxrwxrwx 1 root root 12 Mar 13 12:46 /dev/sd3c -> dsk/c0t0d0s2

Their [?] new style short names:

seismo!wagle[109] ls -l /dev/dsk/c0t0d0s2
lrwxrwxrwx 1 root root 84 Mar 13 12:46 /dev/dsk/c0t0d0s2 -> ../../devices/iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/sd@0,0:c

Which are pointers to a directory hierachy that reflects the device
hierarchy:

seismo!wagle[110] ls -l /devices/iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/sd@0,0:c
brw-r----- 1 root sys 32, 2 Mar 13 12:46 /devices/iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/sd@0,0:c

My points being:

(1) The device HIERARCHY is reflected in the file system. This is
kinda cool.

(2) This hierarchy is build statically, and [usually] only on special
reboot ("boot -r"). This is kinda not so cool, though the commands to
do the builds are available at non-boot-time, I got the impression
from the documentation that their use at non-boot-time was
discouraged.

Maintaining such a tree dynamically would be very interesting, but has
a bunch of problems that I decided to delete from this note.

-- Perry