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: http://superuser.com/questions/119446/sectors-and-clusters http://superuser.com/questions/119051/transfer-time-for-a-file http://superuser.com/questions/107723/hard-drive-sectors-vs-tracks http://superuser.com/questions/119048/number-of-tracks http://superuser.com/questions/119026/rotational-latency http://superuser.com/questions/119030/bytes-per-track — Jonathan Leffler, Mar 16 '10 at 11:06
And http://superuser.com/questions/120461/transfer-time-of-a-cylinder — Jonathan Leffler, Mar 16 '10 at 11:13

score 7 · Accepted Answer · answered Mar 12 '10 at 07:49

7

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

Or, in other words:

30000 / RPM

Result in ms.

answered Mar 12 '10 at 07:49

Alex

1

That would be the average rotational delay. The maximum would be twice that. – Phenom Mar 13 '10 at 05:11
why `0.5 * 1000`? – The Room Oct 17 '18 at 06:37

1 Answers1