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A comment on A 1970s Cray-1 hard drive has been imaged. Parent comment

Re:A 1970s Cray-1 hard drive has been imaged by fhars on Wednesday September 07, 2011 @08:04AM (#2969215)
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.
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Re:A 1970s Cray-1 hard drive has been imaged by mjb on Wednesday September 07, 2011 @08:20AM (#2969251)
We 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.

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