place power on time in a standard log page?

Douglas Gilbert dgilbert at
Sat Sep 11 20:25:57 PDT 2004

* From the T10 Reflector (t10 at, posted by:
* Douglas Gilbert <dgilbert at>
Gerry.Houlder at wrote:
> Kevin,
> Your proposal doesn't provide a method to return "total power on hours".
> You mention a default time of "time since last power on" but this is
> entirely different and won't be the same as total power on hours.
> If a total power on hours timer is not addressed in 04-271, then the most
> reasonable way to include it is to add a total power on hours parameter to
> log page 0Eh. This already contains a "total number of spinups" value, so a
> total power on hours value would be consistent with the purpose of the log
> page.

Log page 0Eh (start stop cycle counter) seems to fit. Unfortunately the
diagram (table 208 in SPC-3 rev20a) shows the page length as 24h, as if
it is a constant but the associated words don't imply that. Parameter code
5h would be the next available one and the name "accumulated power on
hours" should cut down on any confusion. The form of words would be
similar to the paragraph describing the accumulated start-stop cycles
(parameter code 04h) parameter (e.g. 4 byte counter and DS bit set to 1
so it can't be changed with a LOG SELECT).

Perhaps a note could be added saying that the accumulated power on hours
is the value that appears in the timestamp field of the self-test results
log page at the time that self test was performed (unless 0ffffh power on
hours had been exceeded since timestamp is only a 2 byte field).

It is probably a bit late for SPC-3 though.

Doug Gilbert 

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