The header of this post did not really phrase the question correctly.
I was actually asking how to correlate "unit numbers" on the array to rz*
devices on the system. Many people actually answered the actual question,
however, thanks to all who replied so promptly.
The first response I got was quite clear, so I'll quote - thanks
to Martin Moore from the Digital UNIX Expert Team:
--------------------------------------
Unit names on the HSZ family of RAID controllers are of the form Dtzl, where
t = SCSI target ID, z = zero, and l = SCSI lun (this is host-side SCSI target
and lun, i.e., what the UNIX system sees. It has no relation to the internal
SCSI port/target/lun combinations that identify each disk to the HSZ
controller.)
For example, D100 = target 1, lun 0. Leading zeroes may be dropped, e.g., D2
is the same as D002.
To calculate the rz number, you need the SCSI bus number (which you must know
based on your system configuration; the HSZ has no idea which bus number it's
on), the target, and the lun. The device name is rzlnnn, where l = a lun
letter (a-h for 0-7; no letter is the same as a) and nnn = (bus number * 8)
+ target ID.
In your example, /dev/rz33c is rz33 (c is a partition designator). Since
there is no lun letter, this is lun 0; the device could also have been called
rza33. 33=(4*8)+1, so the bus number is 4 and the target ID is 1. We have
target 1 and lun 0, so the unit number on the HSZ is D100.
----------------------------------------
I would like to add, for those who may be as confused as I was initially,
that the SCSI bus number, target ID and lun are visible at boot time, as in:
(4*8)+1=rz_33 rzb33 at scsi4 target 1 lun 1 (LID=38)
- lun 1 makes it rzb32 _(DEC HSZ70 V70Z)
_(Wide16)
rzb33 would be D101, as the lun is 1, as indicated by the "b".
I am still a bit puzzled about the target ID, though, because it seems
rather arbitrary, based on what my field service person said.
We learned through errors that when you have a 5 port hub in the hsz, you
may not set your host id to 7 on the system, as this hub wants that id.
So, we had to change our host id to 4 (we were already using 5 and 6),
which meant we took away the scsi id of 4 from the array itself, leaving it
0,1, and 2. Here's what happened.
We had the following disks:
D300 = /dev/rz19c
D301 = /dev/rzb19c
We removed these units, and rebuilt them as:
D203 = /dev/rzd18c
D204 = /dev/rze18c
Fine. But, the DEC person said we could just as easily have made them:
D103 = /dev/rzd17c (I think)
D104 = /dev/rze17c (I think)
I don't understand how it can be so arbitrary? Can someone explain this
anomaly? I'll summarize soonest.
Many thanks again.
--
Judith Reed
jreed_at_appliedtheory.com
Received on Wed Oct 21 1998 - 13:15:58 NZDT