10. Continuous File Reads From An Internal Hard Drive

Most typical notebook drives fit a 2.5" form factor.

Of course, it's also useful to know how strong an effect the use of the internal hard drive has on battery lifetime. To this end, we copied a very large MPEG file from the internal hard disk to the so-called null device in an endless loop. This sleight of hand allowed us to be sure that the file was accessed solely from the drive (and not from cache or paging files).

A custom-built program continuously reads files from the hard disk until the battery runs dry.

As usual, we continued to write a log entry to a text file every ten seconds so we could monitor battery life time closely. We used a Hitachi TravelStar 5K100 HTS541040G9AT00 for our test, which has 40 GB of capacity and runs at 5,400 RPM.