Can someone explain "Data Phase Error"

Can someone explain "Data Phase Error"

[Greg Freemyer]

All,

Environment:
kernel - 2.6.8-24  (from SUSE 9.2)
tape drive - IBM LTO-1 (scsi-wide)
scsi controller - Adaptec 2940

Issue:
I am trying to build a pair of new Linux based tape servers.

I have written exactly one tape on each, I then swapped the tapes
beween the units and tried to do a restore.  One seems to be working
fine on this first test, but with the other I get:

Dec 17 08:52:04 linux kernel: st0: Error with sense data: Info
fld=0x40000, ILI Current st0: sense = f0 2b
Dec 17 08:52:04 linux kernel: Additional sense: Data phase error

I would suspect a bad tape, but a simple "dd if=/dev/st0 of=/dev/null
bs=256k" fails at a different number of blocks each time.

i.e. I have 130 GB of data on the tape, but I have not yet read back
more than 6 GB of it.  The data itself is unimportant, I'm just
testing the process.

I am continueing to test and am now trying another tape, but I want to
understand this initial failure if I can.

Thanks for any help.
Greg
-- 
Greg Freemyer

Re: Can someone explain "Data Phase Error"

[Greg Freemyer]

I believe I found the problem.

Somehow one of the servers was built with a Adaptec 2940 controller,
and the other with a Adaptec 29160.

Since the 2940 does not support LVD (only SE), I'm pretty sure that is
the issue.

I'm actually surprised that the 2940 based system worked so well.  I
successfully wrote out 300+GB of data and those tapes were restorable
by the 29160-based system.

It was only the restores that were unreliable, and that was true
regardless of where the tapes were written.

Is there a LINUX - SCSI troubleshooting guide that provides advice for
the various SCSI kernel error mesages?  Does it cover this situation?

Greg
-- 
Greg Freemyer


On Sun, 19 Dec 2004 21:01:20 -0700, Eric Mudama <edmudama@gmail.com> wrote:
> are these tapes new?
> 
> I've been told you have to write them 3-4 times before they can be
> written to reliably, since the heads remove particle contamination or
> something like that in those initial passes.
> 
> 
> On Fri, 17 Dec 2004 16:23:24 -0500, Greg Freemyer
> <greg.freemyer@gmail.com> wrote:
> > All,
> >
> > Environment:
> > kernel - 2.6.8-24  (from SUSE 9.2)
> > tape drive - IBM LTO-1 (scsi-wide)
> > scsi controller - Adaptec 2940
> >
> > Issue:
> > I am trying to build a pair of new Linux based tape servers.
> >
> > I have written exactly one tape on each, I then swapped the tapes
> > beween the units and tried to do a restore.  One seems to be working
> > fine on this first test, but with the other I get:
> >
> > Dec 17 08:52:04 linux kernel: st0: Error with sense data: Info
> > fld=0x40000, ILI Current st0: sense = f0 2b
> > Dec 17 08:52:04 linux kernel: Additional sense: Data phase error
> >
> > I would suspect a bad tape, but a simple "dd if=/dev/st0 of=/dev/null
> > bs=256k" fails at a different number of blocks each time.
> >
> > i.e. I have 130 GB of data on the tape, but I have not yet read back
> > more than 6 GB of it.  The data itself is unimportant, I'm just
> > testing the process.
> >
> > I am continueing to test and am now trying another tape, but I want to
> > understand this initial failure if I can.
> >
> > Thanks for any help.
> > Greg
> > --
> > Greg Freemyer
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
>