Networking: A Beginner's Guide
require a lot of administration. Most companies would gladly trade that sort of
extreme cost for some lower degree of recoverability, such as nightly backups
of the system. What does your company need and what is it willing to pay for?
How many levels of redundancy does the company need in its backups? Most
backups are made onto tapes and support servers that use RAID arrays, so the
tapes are actually the second level of protection. In some cases, multiple tapes
may be required, each with a separate copy of the backup. Or another way to
proceed for maximum redundancy is to copy backups to an off-site storage
company over some sort of network connection.
When making your assessment, it is important to involve the senior management
of your company in the process. At a minimum, you should present your findings and
seek management's agreement or input.
Acquiring Backup Media and Technologies
Once you have some idea of your backup needs, you can then proceed to acquire the
necessary hardware and software to create and manage your backups.
If you need to purchase new backup hardware for a system, you can choose from
a number of proven, good systems, depending on your actual needs. When choosing
a backup technology, consider the following factors:
Reliability of the hardware and the media
Cost of the hardware and the media
Likely frequency of restorations
The importance of fitting the entire backup onto a single piece of media
Table 12-1 reviews different types of backup technologies, their approximate costs,
and the relative pros and cons of each. Note that the prices of drives, media, and costs
per megabyte in Table 12-1 are approximations.
If your company can afford digital linear tape (DLT) or Linear Tape-Open (LTO)
systems and can make use of their capacities, you should definitely look into purchasing
this technology. DLT and LTO tapes are rock solid, can be used a rated million times,
and are said to have a shelf life of 30 years. Moreover, the drives are fast for both
backups and restorations. Finally, robotic autochangers are available for DLT and LTO
drives, which means that there is plenty of head room if you outgrow the size of your
drive. Also, the robotic systems are relatively inexpensive and range from small systems
that can hold five tapes up to large libraries that can hold tens or hundreds of tapes.
Some newer backup technologies, such as Super DLT S4 (600GB per tape) and
LTO-4 (800GB per tape), promise to up DLT's ante. For larger networks, these emerging
technologies may make sense. Both DLT and LTO are reliable tape formats with a lot of
support from various computer equipment vendors.