How do you calculate the rotational latency of a hard drive?

Question

If you know the RPM, then how do you calculate the rotational latency?

See this set of 6 closely related questions: superuser.com/questions/119446/sectors-and-clusters superuser.com/questions/119051/transfer-time-for-a-file superuser.com/questions/107723/hard-drive-sectors-vs-tracks superuser.com/questions/119048/number-of-tracks superuser.com/questions/119026/rotational-latency superuser.com/questions/119030/bytes-per-track — Jonathan Leffler, Commented Mar 16, 2010 at 11:06
And superuser.com/questions/120461/transfer-time-of-a-cylinder — Jonathan Leffler, Commented Mar 16, 2010 at 11:13

Alex · Accepted Answer · 2010-03-12 07:49:11Z

7

(1 / (RPM / 60)) * 0.5 * 1000

Or, in other words:

30000 / RPM

Result in ms.

answered Mar 12, 2010 at 7:49

Alex

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1

That would be the average rotational delay. The maximum would be twice that.
– Phenom
Commented Mar 13, 2010 at 5:11
why 0.5 * 1000?
– The Room
Commented Oct 17, 2018 at 6:37

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