Backup Media Storing
Finding a good way to store backups is almost as important as setting up
a schedule to create them. Backups, installation media and boot disks should
be stored in place where only authorized people have access to them. In order
to make restorations as painless as possible, backups need to be easy to get
to and well labeled. Labeling includes clearly marking the medium itself as well
as including a table of contents file so that individual files on the medium can
be found easily. If several people share responsibility for making
backups or a number of different commands are used to create backups, the label
should also include the command used to create the backup. The label is also an
ideal place to keep a running tally of how many times the media has been used and
how old it is.
Most backup media are sensitive to heat, humidity, direct sunlight and dust. So a
cool, dry storage area is best.Keeping backups in the same room as the system may
be convenient, but not the best idea. In a worst case scenario where damage is done
to the room that houses the system, the backup media may be destroyed also.
For safety's sake all backups should be checked to verify that the media is readable.
This can be done using the restore command to list the contents of the media. Some backup
utilities provide full verification of every file on the media, but this is rare.
There are a couple things to consider in terms of backup media life expectancies.
For long term archiving, changing technologies may result in the media becoming obsolete
before it degrades and the information on it becomes unusable. Unfortunately there is no
standard method for determining life expectancy of the media itself. Manufacturers will
frequently give a recommendation on the number of times that the media can be reused as
well as an estimated life expectancy. It is best to stick to the conservative side of these
numbers. The physical lifetime of the media may be much longer than the amount of time it
takes for the information on the media to degrade.
The following is general estimate of how long backup media can to remain stable and usable:
magnetic tape - 1 year, magnetic disks - 5-10 years, optical disks - 30 years,
write-once CDs - 30+ years.
See also: Backup Storage
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