SSC density code's

JoeBre at Exabyte.COM JoeBre at Exabyte.COM
Tue Feb 29 10:31:14 PST 2000


* From the T10 Reflector (t10 at t10.org), posted by:
* JoeBre at Exabyte.COM
*
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Dave - 

It seems to me that maintaining this table would be a maintenance
problem. Industry-wide, how often is a new density introduced? I would
venture to guess that it is well in excess of 1/year. Do we really want
to track all of these introductions in SSC?

With the advent of the Report Density Support command, will initiators
really care what the value of the Density Code is? I believe the various
fields in the returned data for this command allow an initiator to
choose between the supported densities, using the Density Code merely as
an index. As such, I claim there is no need of a master list of Density
Codes. I beleive that each vendor can independently assign Density Codes
in an ad hoc manner.

Because the Report Density Support command makes the Density Codes
self-describing, the Density Codes are fundamentally of a different
nature than the ASC/ASCQ's. The ASC/ASCQ's _do_ require a master list,
as the target cannot tell the initiator what each one means. The table
of ASC/ASCQ's comprise an authority that both the initiator and the
target _need_ to refer to in order to assign meaning to any ASC/ASCQ.

FWIW, while not all of our Desity Codes are listed in the table, the
ones that are listed are correct. 

Joe Breher 
Exabyte Corp 


> -----Original Message----- 
> From: David Peterson [ mailto:dap at storage.network.com
 ] 
> Sent: Monday, February 28, 2000 4:02 PM 
> To: T10 Reflector 
> Subject: SSC density code's 
> 
> 
> Howdy All, 
> A proposal and request: 
> Currently the SSC document contains an appendix that attempts to list 
> all the tape drive density codes. It has come to my attention there is

> no uniform way to allocate a new density code, other than 
> using the next 
> available value. In other words there is no "master list". 
> I would like to remove this appendix in the next revision of SSC (i.e.

> SSC-2) and maintain the table in a similar manner as ASC/ASCQ's, 
> OpCodes, etc... Thus treat the table as the "master list" and maintain

> it under T10. 
> 
> Also, it would really help if all tape drives vendors would review the

> table and let me know if there are any inconsistencies/issues/errors. 
> Comments? 
> 


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RE: SSC density code's Dave - It seems to me that maintaining this table would be a = maintenance problem. Industry-wide, how often is a new density = introduced? I would venture to guess that it is well in excess of = 1/year. Do we really want to track all of these introductions in = SSC? With the advent of the Report Density Support = command, will initiators really care what the value of the Density Code = is? I believe the various fields in the returned data for this command = allow an initiator to choose between the supported densities, using the = Density Code merely as an index. As such, I claim there is no need of a = master list of Density Codes. I beleive that each vendor can = independently assign Density Codes in an ad hoc manner. Because the Report Density Support command makes the = Density Codes self-describing, the Density Codes are fundamentally of a = different nature than the ASC/ASCQ's. The ASC/ASCQ's _do_ require a = master list, as the target cannot tell the initiator what each one = means. The table of ASC/ASCQ's comprise an authority that both the = initiator and the target _need_ to refer to in order to assign meaning = to any ASC/ASCQ. FWIW, while not all of our Desity Codes are listed in = the table, the ones that are listed are correct. Joe Breher 
Exabyte Corp 
> -----Original Message----- 
> From: David Peterson [mailto:dap at storage.network.com] 
> Sent: Monday, February 28, 2000 4:02 PM 
> To: T10 Reflector 
> Subject: SSC density code's 
> 
> 
> Howdy All, 
> A proposal and request: 
> Currently the SSC document contains an appendix = that attempts to list 
> all the tape drive density codes. It has come = to my attention there is 
> no uniform way to allocate a new density code, = other than 
> using the next 
> available value. In other words there is no = ;master list;. 
> I would like to remove this appendix in the = next revision of SSC (i.e. 
> SSC-2) and maintain the table in a similar = manner as ASC/ASCQ's, 
> OpCodes, etc... Thus treat the table as the = ;master list; and maintain 
> it under T10. 
> 
> Also, it would really help if all tape drives = vendors would review the 
> table and let me know if there are any = inconsistencies/issues/errors. 
> Comments? 
> 
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