2 ms·
That's why they say that disk is the new tape. Releative to the sequential data rate, disk seeks are almost as expensive as a robot changing a tape reel used to
by fhars 15y ago
That's why they say that disk is the new tape. Releative to the sequential data rate, disk seeks are almost as expensive as a robot changing a tape reel used to be.
- mjb 15y agoWe aren't there yet, not by a long shot. Taking clock cycles as the base factor, a disk seek on a modern drive (8ms seek, 4GHz CPU) takes 32 million cycles. On the Cray1's 80MHz CPU, 32 million cycles is 400ms which would be really quick for a robot. Tape seek times (for half a tape) are closer to 40s, which is still 100x more. We'll have to wait a while yet before disk is the new tape in terms of cost of seeks, even when comparing the 70s to today. That's only considering latency. The cost consideration is a completely different story.