Mode Parameter changes and when they take effect

Kevin D Butt kdbutt at us.ibm.com
Wed Aug 6 12:09:02 PDT 2008


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I have a question related to Mode Parameters.  I have searched SPC-4 (and 
earlier SPC versions) and cannot find guidance about when the changes to 
mode parameters take effect.  This concern is related to configuration 
settings and differences in expectations of various vendors.
Vendor 1 claims that any change to a mode parameter shall become effective 
immediately and should not cause a device to reboot.
Vendor 2 claims that changes to some mode parameters require a reboot 
before they can be accomplished.  As such the device automatically 
performs a POR on completion of the Mode Select that changes one or more 
of these parameters.
Vendor 3 also claims that changes to some mode parameters require a reboot 
before they can be accomplished.  This device,however, requires that an 
outside entity send a command to force the device to perform a POR.  The 
new values of the mode parameters are not in effect until after the POR.
In another form of when do parameters take effect, the requested change to 
the format (or density) does not occur until a subsequent command (e.g., a 
Format, a Write from BOT, etc.).
Is there any guidance in SPC?
Thanks,
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com



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