November 10th, 2008
Where flash belongs
Putting flash into disk packaging, while convenient, is sub-optimal. Disk latency is so great that no one worries about adding a few hundred microseconds to an I/O. But once you’ve got low-latency storage those microseconds start to add up.
But I didn’t really get the underlying advantage to low-latency I/O until I spoke to David Flynn, Fusion-io’s CTO. He explained why reduced latency enhances system performance.
Sure, lower latency means faster I/Os, but the key is that fewer inflight I/Os frees up the CPU to do real work. Inflight I/Os eat up cache and create interrupts that chew up CPU cycles.
The Storage Bits take
In short, this video is about why flash doesn’t belong in disk drive packaging: flash’s latency advantage is diluted for no good reason. Agree or not, if you are interested in the impact of flash on server architecture you will find David’s discussion thought provoking.
Disks for capacity at low cost. Flash - on PCI-e or ExpressCard - for performance. Now if they’d just get a Mac OS version out!!!
Comments welcome, of course. Disclosure: Fusion-io paid me to make the video. My first reaction to their claims was skeptical but as I’ve learned more I’ve become a fan. Sadly, I have no stock in the company.
Robin Harris has been messing with computers for over 30 years and selling and marketing data storage for over 20 in companies large and small. See his full profile and disclosure of his industry affiliations.
Subscribe to Storage Bits via Email alerts or RSS.
