SOS - SCSI Mode Sense page

Hi,

It would be appreciated if some one could help me on this.

I found a strange issue with NetBackup. It seems NetBackup uses SCSI
Mode Sense page 1D to determin if a tape library has a barcode reader
or not. Is it a right action? I ask it because I don't see page 1D
contains barcode reader information.

What about SCSI Inquiry? Can an application running on a host use
SCSI Inquiry to determin if a tape library has a barcode reader or
not?

BJ
--

lx282828@gmail.com wrote:
> Hi,
>
> It would be appreciated if some one could help me on this.
>
> I found a strange issue with NetBackup. It seems NetBackup uses SCSI
> Mode Sense page 1D to determin if a tape library has a barcode reader
> or not. Is it a right action? I ask it because I don't see page 1D
> contains barcode reader information.

netbackup is sort of the standard of backup software, mostly because it
actually works.

> What about SCSI Inquiry? Can an application running on a host use
> SCSI Inquiry to determin if a tape library has a barcode reader or
> not?

What is the problem you're having with netbackup?

On Dec 12, 6:41 pm, Cydrome Leader <prese...@MUNGEpanix.com> wrote:
> lx282...@gmail.com wrote:
> > Hi,
>
> > It would be appreciated if some one could help me on this.
>
> > I found a strange issue with NetBackup. It seems NetBackup uses SCSI
> > Mode Sense page 1D to determin if a tape library has a barcode reader
> > or not. Is it a right action? I ask it because I don't see page 1D
> > contains barcode reader information.
>
> netbackup is sort of the standard of backup software, mostly because it
> actually works.
>
> > What about SCSI Inquiry? Can an application running on a host use
> > SCSI Inquiry to determin if a tape library has a barcode reader or
> > not?
>
> What is the problem you're having with netbackup?

Thanks for your response.

I probably shouldn't link what I'm not sure to NetBackup. The right
question perhaps is how a tape library report it has a barcode reader
to a backup application? Does it use SCSI Inquiry command or some
other commands?

BJ
--

lx282828@gmail.com wrote:
>
> I probably shouldn't link what I'm not sure to NetBackup. The right
> question perhaps is how a tape library report it has a barcode reader
> to a backup application? Does it use SCSI Inquiry command or some
> other commands?

If the library contains a SPC4/SMC3 compliant media changer, like this:

First the INQUIRY command reports in the "Peripheral Device Type" field
of the standard response that this logical unit is a medium changer
(08h).

Now a MODE SENSE command can be send to read the Device Capabilities
Page (1Fh). If the VTRP (Volume Tag Reader Present) bit is set, there is
Volume Tag hardware implemented. MODE SENSE is an optional command. If
it is not implemented, it is IMHO allowed to assume that no Volume Tags
are supported (see below).

If the VTRP bit is set, a READ ELEMENT STATUS command can be send with
the VOLTAG bit set. The element status pages in the response should
contain the bits PVOLTAG [and maybe AVOLTAG] indicating that Volume Tags
are supported. READ ELEMENT STATUS is a mandatory command but it is not
allowed to set the VOLTAG bit if Volume Tags are not supported
(therefore if MODE SENSE is not implemented, this bit must be cleared).

Note:
Because Volume Tags can be implemented using different methods, it is
not possible to detect whether a media changer uses a barcode reader or
something else to provide Volume Tag support.


Micha

On Dec 14, 6:10 am, Michael Baeuerle <michael.baeue...@stz-e.de>
wrote:
> lx282...@gmail.com wrote:
>
> > I probably shouldn't link what I'm not sure to NetBackup. The right
> > question perhaps is how a tape library report it has a barcode reader
> > to a backup application? Does it use SCSI Inquiry command or some
> > other commands?
>
> If the library contains a SPC4/SMC3 compliant media changer, like this:
>
> First the INQUIRY command reports in the "Peripheral Device Type" field
> of the standard response that this logical unit is a medium changer
> (08h).
>
> Now a MODE SENSE command can be send to read the Device Capabilities
> Page (1Fh). If the VTRP (Volume Tag Reader Present) bit is set, there is
> Volume Tag hardware implemented. MODE SENSE is an optional command. If
> it is not implemented, it is IMHO allowed to assume that no Volume Tags
> are supported (see below).
>
> If the VTRP bit is set, a READ ELEMENT STATUS command can be send with
> the VOLTAG bit set. The element status pages in the response should
> contain the bits PVOLTAG [and maybe AVOLTAG] indicating that Volume Tags
> are supported. READ ELEMENT STATUS is a mandatory command but it is not
> allowed to set the VOLTAG bit if Volume Tags are not supported
> (therefore if MODE SENSE is not implemented, this bit must be cleared).
>
> Note:
> Because Volume Tags can be implemented using different methods, it is
> not possible to detect whether a media changer uses a barcode reader or
> something else to provide Volume Tag support.
>
> Micha

Thanks Micha, It helps a lot!

Best regards,

BJ
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