Information Technology Reference
In-Depth Information
areas, even creating a copy of all system parameters needed for bare-metal
recovery in the event of total hardware loss. Virtualized server recovery
extends this capability to a hardware-agnostic level of abstraction, allow-
ing recovery of virtualized systems to any other platform running the
same virtual hosting protocol by simply copying the necessary virtual
system files to a new host and reactivating the virtualized server.
Media Retirement
Storage media is only pristine until it has been used to store actual data.
Once this has occurred, it may be repeatedly reused, overwritten, and
erased, but it will never again be entirely free of all traces of the informa-
tion that was stored in it. Because this information has value as an asset,
and may represent a liability if accessed by unauthorized means, its even-
tual retirement must be included in storage policy planning.
Media Erasure
Because file deletion and even drive reformatting may only remove file
storage entries, secure erasure should be the minimum standard for
retired media. Secure erasure utilities employ successive overwriting of
data, using all 1's, all 0's, and random information to effectively eliminate
or mask previously stored magnetic data. Very powerful magnets may
also be used to saturate the magnetic media, erasing not only the surface
data but also randomizing magnetic potentials deep within the media
substrate as well. The latter method of erasure requires dedicated equip-
ment, but it can be performed on drives that no longer operate. Erasure of
rewritable optical media can also be performed through secure overwrit-
ing, though the chemical changes used to write information can still be
used to reconstruct overwritten information from discarded media.
Physical Destruction
A better solution for optical media involves physical destruction of the
media itself. While some shops may use a microwave oven to destroy the
metallic layer on optical disks, this yields incomplete media destruction
and releases noxious gases that present a health risk. A better solution
