[T10] Direction for 17-042 proposal

Gerry Houlder gerry.houlder at seagate.com
Fri Apr 7 13:51:33 PDT 2017


Hi,

This proposal adds a bit to a VPD page to indicate that a deferred download
has completed but has not yet been activated. A VPD bit is appropriate
because it is a bit that is only changeable by the SCSI target device (not
an application client) and is a bit that is desired for discovery process.
A slight disadvantage (for making this translatable for SATA) is that the
drive must establish a Unit Attention when the INQUIRY data changes -- this
is not easily translatable to SATA.

An alternate model for this feature is to use a mode page bit. The bit
would be marked as not changeable by the host but the target device would
set and clear the bit according to the presence of deferred microcode.
There would not be a requirement to establish a Unit Attention for mode
parameters changed because this Unit Attention is defined for changes made
by an application client. This would eliminate the need to simulate a Unit
Attention in the SATA version of this feature (which is not desired in T13).

I am asking for opinions ahead of the April T13 meeting and May T10 meeting
as to whether a VPD bit or a mode page bit is the preferred direction for
T10. At the moment, it seems that changing to a mode page bit is the better
direction. Feel free to give feedback on the T10 reflector.
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