Saveable mode pages

Gerry Houlder gerry.houlder at
Wed Feb 11 18:36:45 PST 2015

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It is interesting that SPC-4 promises behavior of FORMAT UNIT command when
FORMAT UNIT command is not included in SPC-4 and there isn't even a "see
command standard" reference. I think you would be happier with a statement
like "Saveable mode pages may also be saved by a FORMAT UNIT command (see
SBC-4 and SSC-x)". i guess we missed this during letter ballot review last
On Wed, Feb 11, 2015 at 4:02 PM, Kevin D Butt <kdbutt at> wrote:
> I am confused by *6.12.5 Saved values*
> <<All saveable mode pages should be considered saved if a MODE SELECT
> command issued with the SP bit set to one has completed with a GOOD
> status or after the successful completion of a FORMAT UNIT command.>>
> This states that after the successful completion of a FORMAT UNIT command
> ALL saveable mode pages should be considered saved. This may be good for
> block devices, but why are tape devices included in this? On tape devices a
> FORMAT UNIT command formats the tape but does not change other things in
> the device - nor do we want it to.  Also, I can interpret this to say, when
> doing a FORMAT UNIT command part of the processing is to take all the
> Current values of mode pages that are saveable and save them. This may
> violate the intent of the application client which explicitly did not set
> the SP bit in the MODE SELECT that updated the Current values (and
> explicitly did not update them to Saved values).
> Is anybody else bothered by this?
> Kevin D. Butt
> SCSI Architect, Tape Firmware, CAMSS
> T10 Standards
> MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
> Tel: 520-799-5280
> Fax: 520-799-2723 (T/L:321)
> Email address: kdbutt at

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