magnetic recording

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The recording of a signal, such as sound or computer instructions, in the form of a magnetic pattern on a magnetizable surface for storage and subsequent retrieval.
• noun A surface containing a magnetic recording.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The recording of a signal; sound or image, on a magnetizable vessel or medium for storage, and retrieval purposes.