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SubjectRe: 3940UW Driver Locks the Machine


I donnot have a Jaz device. Based on reports and especially on Richard
Waltham testings with such a device, it seems to me that the Jaz may in
certain circumstances reject a TAG (after having been selected).
The SCSI specs allow that to targets when they are in some initialisation
process and, AFAIR, the initiator is invited (required?) to perform the
command as if the command was not TAGGED.
Implementing such a behaviour is pain in the ass, since several TAGGED
commands may have been queued to drivers and/or controllers when a TAG
is so rejected.
IMO, this would require additionnal complexity in scsi drivers
in a way that may affect performances and reliability.

Note that the device may claim to be in some initialisation process
only after a reset and while it is spinning up.


Gerard.


On Sun, 15 Feb 1998, Andreas Haumer wrote:

> Hi!
>
> Robert L Harris wrote:
> >
> > When I try and read files off my jaz, usually it seems to lock my machine.
> > It locks the scsi activity light on and if I can get to the console I get
> > alot of errors concerning the queue. This time I didn't change the adapter
> > defaults.
> >
> > Who do I work with to see about fixing this?
> >
> Try disabling command queueing for the JAZ device in the adapter
> setup. This helped for me, though I have to admit that a SCSI device
> shouldn't completely lock up the system.
>
> With a ncr53c8xx-based board the JAZ drive still doesn't work well with
> command queueing, but the driver doesn't completely lock up the machine,
> it returns an error code after a short timeout and continues working.
>
> With command queuing turned off for the JAZ drive it works stable and
> well!
>
> Hope that helps!
>
> - andreas
>
> --
> Andreas Haumer | email: andreas@xss.co.at | PGP key available
> *x Software + Systeme | phone: +43.1.6001508 | on request.
> Buchengasse 67/8 | +43.664.3004449 |
> A-1100 Vienna, Austria | fax: +43.1.6001507 |
>
> -
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>
>


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