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METHOD FOR TRACKING POWER-ON TIME OF A DEVICE WITH NO OVERHEAD

IP.com Disclosure Number: IPCOM000013732D
Original Publication Date: 2000-Apr-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Abstract

Described is a method to record accumulated power-on time in a device without having having to use any extra storage space. This method applies to devices with non-volatile storage managed as a file system, where the files have time stamps. The time stamps may all be written as the accumulated power-on time of the device instead of absolute time (or no time at all). At power-on, the machine’s accumulated power-on time may be determined by reading the time stamps, and then incremented as the machine operates. No extra storage is needed in the non-volatile storage devices. The accuracy of the time calculated at power on will be determined by how often files are changed, since power-on time that occurs between the last update of a file and power off is lost. If the device has to update files frequently for other reasons, the precision would be quite good. If not, files can be updated periodically to force better precision, though at the cost of more wear on the device. This methodhas the following elements:

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METHOD FOR TRACKING POWER-ON TIME OF A DEVICE WITH NO OVERHEAD

   Described is a method to record accumulated power-on time in a device without
having having to use any extra storage space.

This method applies to devices with non-volatile storage managed as a file
system, where the files have time stamps. The time stamps may all be written
as the accumulated power-on time of the device instead of absolute time (or no
time at all). At power-on, the machine's accumulated power-on time may be
determined by reading the time stamps, and then incremented as the machine
operates. No extra storage is needed in the non-volatile storage devices.

The accuracy of the time calculated at power on will be determined by how
often files are changed, since power-on time that occurs between the last
update of a file and power off is lost. If the device has to update files
frequently for other reasons, the precision would be quite good. If not,
files can be updated periodically to force better precision, though at the
cost of more wear on the device.

This methodhas the following elements:

At start-up of the device, the time stamps of some or all of the files in
the file system are examined; and interpreted as indicating the amount of
accumulated power-on time the device had recorded at the time that file
last changed, rather than the time at which the last change occurred; and
the largest indicated amount of accumulated power-on time is remembered;

When a file is changed, the space allocated in the file system for
recording the time-of-last change is not written as the current time.
Instead, the amount of accumulated power-on time remembered at power-on is
added to the elapsed time since the device power was turned on; and that
result is stored in the file's time stamp in the non-volatile storage
device.

This method has the following variat...