adaptec 2940u/uw dump card state ends

[Don Lewis]

On 22 Jan, Jesse Guardiani wrote:
> Jesse Guardiani wrote:
> 
>> Howdy list,
>> 
>> I'm having trouble with a Sony AIT TSL-SA300C autochanger
>> attached to an adaptec 2940u/uw SCSI card and a Seagate AIT
>> tape drive. Hopefully someone can shed some light on my
>> problem.
>> 
>> The physical (as in cable) SCSI topology looks like the
>> following, with terminated devices marked by a (T):
>> 
>> (T)AIT Autochanger <-> 2940u/uw <-> Seagate AIT Tape(T)
>> 
>> I have termination manually turned off in the 2940u/uw's
>> software configuration utility. The Seagate AIT tape drive
>> is terminated via jumper (Term PWR is off, and SCSI Term
>> is ON, if I remember correctly). The Sony Autochanger is
>> terminated using a long yellow external wide SCSI ribbon
>> cable. The cable has a little black thing on the end that
>> I am ASS-U-MEing is a resistor pack for termination. The
>> Autochanger's PDF indicates that it is not capable of
>> active termination, which makes sense because it's external
>> and you can turn it off.
>> 
>> Admittedly, termination may be the issue. I'm relatively
>> new to SCSI, and I may not have gotten it right. In
>> particular, I don't have a clue what the TERM PWR jumpers
>> do on devices that also include a SCSI TERM jumper...
>> 
>> Here is the problem I'm having:
>> 
>> The first time I issue a `chio move drive 0 slot 0` command,
>> I get this:
>> 
>> (ch0:ahc0:0:2:1): SCB 0xe - timed out

Just a guess ... maybe the changer mechanism requires a longer time than
what the driver thinks.  At the top of /usr/src/sys/cam/scsi/scsi_ch.c
there is the following:

/*
 * Timeout definitions for various changer related commands.  They may
 * be too short for some devices (especially the timeout for INITIALIZE
 * ELEMENT STATUS).
 */
          
static const u_int32_t  CH_TIMEOUT_MODE_SENSE                = 6000;
static const u_int32_t  CH_TIMEOUT_MOVE_MEDIUM               = 100000;
static const u_int32_t  CH_TIMEOUT_EXCHANGE_MEDIUM           = 100000;
static const u_int32_t  CH_TIMEOUT_POSITION_TO_ELEMENT       = 100000;
static const u_int32_t  CH_TIMEOUT_READ_ELEMENT_STATUS       = 10000;
static const u_int32_t  CH_TIMEOUT_SEND_VOLTAG               = 10000;
static const u_int32_t  CH_TIMEOUT_INITIALIZE_ELEMENT_STATUS = 500000;

I think these times are milliseconds.  The scsi command that you are
using may be using one of these timeouts: CH_TIMEOUT_MOVE_MEDIUM,
CH_TIMEOUT_EXCHANGE_MEDIUM, or CH_TIMEOUT_POSITION_TO_ELEMENT (I'm not
very familiar with changers).  These appear to be set to 100 seconds, so
if your changer takes longer than this, the driver will time out the
command before the changer indicates that it is finished.  Try bumping
these up and rebuild your kernel.  They should probably be tunable ...

>> 
>> 
>> So far, all further commands have been successfull.
>> 
>> Here's my uname:
>> 
>> # uname -a
>> FreeBSD billmax.int.wingnet.net 4.9-RELEASE FreeBSD 4.9-RELEASE #0: Sun
>> Jan 18 18:29:28 EST 2004    
>> jesse at billmax.int.wingnet.net:/usr/src/sys/compile/BILLMAX  i386
>> 
>> Any suggestions?
> 
> Surely someone on the -SCSI list can at LEAST answer my simple questions
> about TERM PWR vs SCSI TERM jumpers on drives....
> 
> I'd love to know why I'm getting the above timeout too, but if someone
> could just verify the difference between TERM PWR and SCSI TERM, and
> how they should be used then I can at least get a starting point.

One of the wires the SCSI bus (TERMPWR) is used to supply termination
power to any passive terminators (or active terminators without their
own power source) at the ends of the bus.  Usually you will want the
host adapter to supply termination power.  Peripherals also commonly
have jumpers or switches that can be set to cause them to supply power
to the TERMPWR line.  If the peripheral has a jumper labeled TERM PWR,
it is used to supply power to the TERMPWR line on the SCSI bus.  As I
recall, no more than two devices should power the TERMPWR line, to limit
the amount of current that would flow if the TERMPWR line is shorted to
ground, so that nothing catches on fire.

Many peripherals are also able to terminate the bus so that an external
terminator is not needed.  This is typically done by setting a jumper or
switch, or plugging a resistor pack into a socket on the peripheral.  If
the peripheral at the end of a bus is used to terminate the bus instead
of using an external terminator, the power for the terminator can either
be taken from the power supplied to the peripheral, or from the TERM PWR
line on the SCSI bus.  You would want to do the latter if you want the
bus to operate properly even if power to the peripheral is shut off.

I typically use Seagate SCSI disks which have two jumper positions to
control termination and termination power.  I believe there are five
different jumper arrangements allowed (at least for single-ended SCSI)
for the different termination configurations.

When the host adapter is at one end of the bus, I prefer to let it feed
TERMPWR along with the peripheral at the other end of the bus (assuming
that it is always powered on), so that the power to the terminator at
the far end of the bus is as clean as possible.