Wednesday, August 17, 2005


Subject: Re: sd.conf

You can remove all entries in the sd.conf file that have target=n lun=m
with n!=5 and m>0 for your system. It takes 1/4 second to determine
that a target ID is not responding. My guess is that by adding the
additional lun entries for those targets which aren't present, the
software is spending 1/4 second per lun (even though it really shouldn't
have to).

The target ID is the same as the SCSI ID on the SCSI bus.
The lun value is a Logical Unit Number for a given target id.

The data shown below identifies the device as cntndn. c1 is the
controller number. tn is the target id. dn is the LUN. So the entries
you show below identify that your system has a controller #1 (c1) with
target ID 5 (t5) and two LUN's (d0 and d1).

If a target ID doesn't respond to a SCSI selection (selection timeout)
then no LUN's can exist for that target ID. This is why you can remove
all entries for those ID's which you don't have attached to your bus.
If a target ID does respond but the LUN is not available, the time to
determine that a LUN is not available is minimal (probably in
microseconds range). So it doesn't hurt to leave all LUN's enabled for
target ID 5 even if you only are using two of them.


- Hide quoted text -


Post a Comment

<< Home