Summary: Lehrstuhl für Informatik 9
Zeit: Donnerstag, 08.05.2008, 16.30 Uhr
Ort: AH I, Ahornstr. 55
Referent: Götz Graefe, Ph.D.
HP Labs, Palo Alto
Titel: The five-minute rule twenty years later,
and how flash memory changes the rules
In 1987, Gray and Putzolo presented the five-minute rule, which was reviewed and
renewed ten years later in 1997: A database record (or page) should be kept in
memory if it is accessed more often than every five minutes; otherwise, it should re-
main on disk and read when needed.
With the advent of flash memory in the gap between traditional RAM main memory
and traditional disk systems, the five-minute rule now applies to large pages appro-
priate for today's disks and their fast transfer bandwidths, and it also applies to flash
disks holding small pages appropriate for their fast access latency.
Flash memory fills the gap between RAM and disks in terms of many metrics: acqui-
sition cost, access latency, transfer bandwidth, spatial density, and power consump-
tion. Thus, within a few years, flash memory will likely be used heavily in operating