NEW INFO ON READ(6)

GFRAZIER at AUSVM6.VNET.IBM.COM GFRAZIER at AUSVM6.VNET.IBM.COM
Wed Sep 4 06:00:24 PDT 1996


* From the SCSI Reflector (scsi at symbios.com), posted by:
* GFRAZIER at AUSVM6.VNET.IBM.COM
*
A week or so ago, we sent this reflector a note asking for opinions
on the committees recent decision to make Read(6) optional. Since then
we've received several comments. Most of them gave examples of existing
systems which require Read(6) for boot. They also pointed out that drive
vendors will continue to implement Read(6) whether it is optional or not.
Making Read(6) optional, therefore, does not save the drive vendors any
work. Instead, it creates problems for system vendors because they can
no longer offer existing customers a GUARANTEE that they can use SCSI-3
drives.

Also, a new problem has been identified with P1275 (Open Boot):
The P1275 Firmware specification requires the use of Read(6) if the
target block is below 512 MBy. It then specifies that if the drive returns
an error, the error routine must report that nothing has been read--it does
NOT specify to use Read(10). This means that a program which meets P1275
cannot boot from drives which have the boot record in the lower 512 MBy
and which do not support Read(6).   (For details, please see P1275, Section
E.6.5, scsidisk.fth.)

Given the above comments and the P1275 specification, I would like to
reconsider the Read(6) decision at next week's work group.

Giles Frazier
IBM Austin
gfrazier at ausvm6.vnet.ibm.com
*
* For SCSI Reflector information, send a message with
* 'info scsi' (no quotes) in the message body to majordomo at symbios.com




More information about the T10 mailing list