Revisiting the Five-Minute Rule

In 1987, a study published by Jim Gray and Gianfranco Putzolu evaluated the trade-offs between holding data in memory and storing it on a disk. Known widely as the "five-minute rule," their research was updated and expanded 10 years later. Now, as jamie points out, Communications of the ACM is running an article by Goetz Graefe with another decennial update, evaluating the rule using hardware and software typical of 2007, with an eye toward how flash memory will affect the situation. An excerpt from Graefe's conclusion: "The 20-year-old five-minute rule for RAM and disks still holds, but for ever-larger disk pages. Moreover, it should be augmented by two new five-minute rules: one for small pages moving between RAM and flash memory and one for large pages moving between flash memory and traditional disks. For small pages moving between RAM and disk, Gray and Putzolu were amazingly accurate in predicting a five-hour break-even point two decades into the future. Research into flash memory and its place in system architectures is urgent and important. Within a few years, flash memory will be used to fill the gap between traditional RAM and traditional disk drives in many operating systems, file systems, and database systems."

Comments

Re:Not to be confused with

[ZosX]

I adhere to the 30 second rule myself.... :)

I'm still not clear on this....

[ZosX]

Isn't it still the case the flash drive speed slowly degrades as they fill up and delete blocks, as it marks blocks off as used even though they are half full, etc? And that windows 7 is going to somewhat address this issue? Also, are their claims now that you can get millions of writes still holding water? I'm not real convinced yet. The speed is there, but there still seem to be fundamental issues. Like for instance, this PC I'm using right now is a backup machine, and its old 40gig drive is really slow. I can boot linux off a USB flash drive. Would that be any faster, and more importantly, how long would the usb drive last from swapping? Theoretically it should be faster and throughput should be higher with USB 2. I'd only need like a 16 gig stick or something......

Re:I'm still not clear on this....

[Lemming Mark]

Guess it might be faster for some stuff but I'm guessing it'd probably be slower overall. USB flash sticks are quite different animals to the SSDs you get as hard drive replacements. Although they're both based on flash memory tech, AFAIK SSDs typically provide much higher performance (and because they're not running over USB you may also find they have lower CPU usage in operation and may reach higher bandwidths in practice).

If you want to make your existing machine fast you could install something like Puppy Linux, which IIRC runs itself entirely out of a ramdisk. You can boot that off CD-R / CD-RW or a USB stick and it'll run straight out of RAM the whole time, then save any configuration changes back to the CD-R / CD-RW / Flash stick when you shut down. It's small, wicked fast, includes Firefox. When my main PC's hard drive died I simply stuck a Puppy CD in the drive and used that for browsing, e-mail, etc until the replacement arrived.

Re:What article?

[digitalaudiorock]

Wow...almost nothing but offtopic and redundant posts so far. As for me...I misread the title and assumed it was about eating a Cheeto that fell on the floor.

Re:What article?

[Smivs]

Wow...almost nothing but offtopic and redundant posts so far.

Well, this is /. What do you expect?