rotational latency

from WordNet (r) 3.0 (2006)

rotational latency
    n 1: (computer science) the time it takes for a specific block
         of data on a data track to rotate around to the read/write
         head [syn: {rotational latency}, {latency}]

from The Free On-line Dictionary of Computing (8 July 2008)

rotational latency

   The time for the start of the required {sector} on a disk to
   appear underneath the read/write head.  The worst case is
   where it has just passed the head when the request is
   received.  For a {disk drive} with N heads per surface,
   rotating at R revolutions per minute, the average rotational
   latency will be

   	L = 30/NR seconds.

   Rotational latency is one component of {access time}.