OPC parameters

Dimiter Popoff tgi_earth at yahoo.com
Tue Jan 31 17:37:30 PST 2006


* From the T10 Reflector (t10 at t10.org), posted by:
* Dimiter Popoff <tgi_earth at yahoo.com>
*
Could well be, I have not investigated it.
I'll look into it yet again.. this is what
my posting was about, it is so easy to overlook
something in a document as large as MMC-5, no
matter how well organized it is (which it is
indeed).

Many thanks for the hint!

Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------



--- David Burg <daviburg at windows.microsoft.com> wrote:

> I believe the SET STREAMING command with a
> Performance descriptor is the
> currently preferred command to set speed. I might be
> wrong.
> 
> Best regards,
>  
> David Burg.
> 
> -----Original Message-----
> From: Dimiter Popoff [mailto:tgi_earth at yahoo.com] 
> Sent: Tuesday, January 31, 2006 3:55 PM
> To: David Burg; t10 at t10.org
> Subject: RE: OPC parameters
> 
> After I posted my question yesterday, and, well,
> after some more reading of MMC-5, I must say the
> document is stating clearly enough that the
> right thing to do is to use the GET PERFORMANCE
> command (in fact, it is about the only thing one can
> do :-) in order to obtain the usable write speeds.
> 
>  SEND OPC PARAMETERS is unlikely to be obsoleted
> because it is the only way to set a desired write
> speed (at least the only way I could find).
>  The DoOPC bit will probably also stay useful in the
> future as it provides means to initiate device
> calibration regardless of its former related state.
> On the other hand, there is no problem to send
> the OPC parameters with all zeros following the
> speed word (and DoOPC set to 0), the target
> then (at least the one I have here...)
> just does the calibration if necessary
> when it receives the next write command prior to
> beginning of the actual writing (calibration
> takes several seconds, I would say about 5, so there
> are no timeout issues with that that I would 
> be concerned about).
> 
> Dimiter
> 
>
------------------------------------------------------
> Dimiter Popoff               Transgalactic
> Instruments
> 
> http://www.tgi-sci.com
>
------------------------------------------------------
> 
> 
> 
> --- David Burg <daviburg at windows.microsoft.com>
> wrote:
> 
> > This is more a question than an answer:
> > 
> > Isn't OPC set by the host going obsolete and
> > replaced by automated and
> > transparent OPC within the device alone?
> > 
> > Best regards,
> >  
> > David Burg.
> > 
> > -----Original Message-----
> > From: owner-t10 at t10.org [mailto:owner-t10 at t10.org]
> > On Behalf Of Dimiter
> > Popoff
> > Sent: Monday, January 30, 2006 7:22 PM
> > To: t10 at t10.org
> > Subject: OPC parameters
> > 
> > * From the T10 Reflector (t10 at t10.org), posted by:
> > * Dimiter Popoff <tgi_earth at yahoo.com>
> > *
> > I am trying to figure out how to discover which
> > write
> > speeds are to be used on a given disk.
> > I read MMC5 and it does a great job (I am almost
> > finished now), here goes my question.
> >  With a new disk just inserted there are no OPC
> > entries 
> > in the data returned by the READ DISC INFORMATION
> > command.
> > After I issue a SEND OPC INFORMATION with no data
> (0
> > transfer
> > length) and the DoOpc bit set to 1, the drive does
> > some work
> > and next READ DISC INFORMATION returns some OPC
> data
> > which look good (sligthly different for different
> > disks etc.).
> > However, there is only a single OPC descriptor
> > there;
> > whereas using the GET PERFORMANCE command with a 3
> > (i.e. OPC info requested), I get are a number
> write
> > speeds,
> > different on different disks (media).
> >  How do I find out which speeds to send with an
> SEND
> > OPC
> > INFORMATION command in order to selece and
> calibrate
> > for
> > one of the speeds the disk is meant to? GET
> > PERFORMANCE 
> > will do the job, but it is mandatory only for
> > streaming
> >  devices, presumably it might not be there on some
> > (not a
> > big issue for me, I have - alas - no large
> volumes,
> > but 
> > I am trying to do the right thing if the extra
> cost
> > will
> > not be too high).
> > Just sending all thinkable speeds with DoOpc? I
> have
> > not
> > tried that out still but it will likely waste too
> > much
> > time - I am not sure the drive will know which
> > speeds
> > make sense to work on at all and which not, what
> if
> > it
> > decides to blindly do all - most of them probably 
> > inapplicable - speed calibrations.
> > 
> >  Thanks in advance. I realise the answer is
> probably
> > in the MMC5, but well, it has become pretty bulky
> > over the years and I would welcome some help, I
> > believe
> > I ask the obvious to at least some of you.
> >  And I guess here is the right place to thank the
> > group
> > for making the documents good as they are.
> > 
> > Dimiter
> > 
> >
>
------------------------------------------------------
> > Dimiter Popoff               Transgalactic
> > Instruments
> > 
> > http://www.tgi-sci.com
> >
>
------------------------------------------------------
> > 
> > 
> > 
> > 
> > 
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