[Info-vax] Error using fibre channel target on FreeBSD from OpenVMS

[Matthew R. Wilson]

On 2022-04-24, Robert A. Brooks <FIRST.LAST at vmssoftware.com> wrote:
> On 4/24/2022 2:18 AM, Matthew R. Wilson wrote:
>> This could be a long shot, but I'm hoping to experiment with OpenVMS
>> clustering using a shared system disk over fibre channel.
>> 
>> My two VMS systems are Integrity rx1600s. I'm trying to use a system
>> running FreeBSD as the target. After much experimentation and
>> troubleshooting, I've gotten pretty far, but the volumes are still
>> stuck "offline" in OpenVMS.
>
> I'm inferring that there is no fibre switch between VMS and the
> "storage array".
>
> VMS does not support FC-AL (arbitrated loop).

There is a fibre switch (QLogic SANbox 5802V).

It feels like it *should* be working because the OpenVMS system does see
the LUNs and even assigns them device names (DGA1 and DGA2 corresponding
to UDID 1 and UDID 2 that I assign on the target side), they're just
frustratingly stuck "offline" with an error.

I've turned debug logging up pretty high on the FreeBSD side, and I'm
not seeing anything that looks like a SCSI command error or anything
like that. So I wonder if there's just some magic bit in some
inquire/sense data that needs to be set to make OpenVMS happy. Even if
there's some SCSI command that FreeBSD target support doesn't implement,
it'd be nice to know what command it is so that I could try to add it to
FreeBSD.

Looking at various historical documentation from various SAN vendors, I
see many products had things like an "OpenVMS host mode". This would let
you set UDID, but I suspect they also know of some other values you need
to return in response to certain SCSI/FC commands to satisfy VMS. At
some point someone at SAN vendors knew what the magic was...but I can't
find it documented anywhere.

Is there any way to know what the error is on the VMS side? If I run
ANALYZE/ERROR/ELV and then have it TRANSLATE to an output file, I don't
see anything obvious. I just booted the server up, and here's
everything:

<https://mattwilson.org/filedrop/20220425-vms-error-log.txt>

There are no entries with class DEVICE_ERRORS, but I do see a couple
TIMEOUTS and ATTENTIONS. SHOW ERROR currently reports:

Device                           Error Count
IVMS1$DQA1:                              1
$1$DGA1: (IVMS1 FGA)                     2
$1$DGA2: (IVMS1 FGA)                     2

In the error log there are 4 "ATTENTIONS" and 1 "TIMEOUTS", so perhaps
the timeout is DQA1 and the 4 attentions correspond with the four DGA
errors?

Is there a way to know what the attentions mean? "Device type 54, OS
flags 0x0001" doesn't really pin down the potential problem!

Thanks,
Matthew