AHA2790UW has speed-limit problems ?

[Mike Bilow]

Matti Aarnio wrote in a message to Mike Bilow:

 MA> The Kludge-Cure:

 MA>   Lower the speed of the device in the adapter bios
 MA> configuration utility.  In fact lower them all, and no
 MA> SCSI-timeout problems appear. 

 MA> Question:

 MA>   Is there ANYTHING that is possible to do to in this type
 MA> of environment so that I could (reliably) run faster
 MA> disk-transfer speeds ? Now my RAID0 write throughput has
 MA> dropped from 12.odd MB/sec to 7.odd MB/sec speed.

Yes, I have seen this before in connection with misconfiguration of termination
power, as distinct from termination.  Most drives these days default to
supplying their own termination power, but Adaptec (and the standard) say that
the initiator should be the sole supplier of termination power to itself and to
all other devices on the bus.  This becomes particularly important when you use
active termination, since the active devices used to terminate will cause
ringing with multiple supply points.
 
-- Mike



To Unsubscribe: send mail to majordomo at FreeBSD.org
with "unsubscribe aic7xxx" in the body of the message