Deciding What Type of Storage is Right for You
Online Storage:
When I say online, I'm not referring to the Internet. Here online refers to a backup that is readily accessible by users on the network. For a home WLAN, online storage could consist of a hard disk (or disks) on one of the computers on the network or an external hard drive attached to a PC or with its own Wi-Fi NIC. The idea is that the stored data is instantly accessible by anyone on the network who needs it.
Online storage should offer some sort of redundancy. For a small business the best solution is disk-mirroring using RAID systems. At one time RAID stood for Redundant Array of Inexpensive Disks. Now that all hard disks are relatively inexpensive it stands for Redundant Array of Independent Disks. A RAID system mirrors, or writes, data across several hard drives at once. It makes two or more copies of all your data so that if one hard drive should fail, the duplicate(s) can take its place without the users even knowing about it.
There are several different types, or levels, of RAID system. These are numbered and you may hear people talk about RAID 0, RAID 3, RAID 5, and so on. Just be aware that it is an option for online storage, using a small server if you should decide that it's the way you want to go.
Note: For more information on configuring and using RAID systems, consult Highly Available Storage for Windows Servers (VERITAS Series) by Paul Massiglia (John Wiley & Sons, 2001).
Online storage isn't a replacement for offline storage because it is still susceptible to a number of threats. It has the advantage of being convenient, both when conducting backups and for retrieving data, but for security's sake combines it with periodic offline backups.
Insider insight: When using online storage on a WLAN, consider the bandwidth you will require when backing up over the WLAN and plan large backups at off-peak times. While backing up or retrieving data on a WLAN, the bandwidth available to other users will drop significantly and affect network operation.
Near line Storage:
Near line storage means backing up data to removable media and storing the media onsite. The data can be on CD-R, DVD-R, optical disk, or tape. When you need it, it's available quickly. Often near line storage systems use some sort of tape changer or "jukebox" with storage media preloaded and ready to go when needed .
Like online storage, you can access data on a near line storage system relatively quickly. However, because data is stored on removable media, it is a little more secure. Still, the ultimate insurance is offline and offsite storage.
Note: Norton Ghost is a useful application for creating images of hard disks and burning them to CD-R for data storage and recovery purposes. Norton Ghost is available from Symantec at www. Symantec. com/sabu/ghost/ gbost_personal.
Offline Storage:
Offline storage consists of copying data to removable media that can be stored away from the network. Typical media include magnetic tape, CD-R, or DVD-R. This is especially useful for mission-critical data or personal data that would be hard or impossible to replace. Even if data is needed in real time, offline storage is a safe way to secure copies of it in case of disaster. Store discs in a secure place, such as a safe, and consider keeping an additional copy at a site in a different geographical location (offsite storage).
Selecting media for backups:
Insider insight: Always store your backup media in a secure place. It makes no sense to take care in securing your WLAN, only to leave copies of data lying around where an individual could easily copy or swipe them.
The type of storage media you select affects the cost of your backup system as well as the speed of access and space required to store backups. Media reliability is also important. It must be able to maintain the integrity of data without failing due to degradation from age or mechanical wear and tear.
Different media are available for backing up data. They vary in capabilities and each has its strong and weak points. For my purposes, I present only the most commonly used media in home and small office settings.
Internal/External Hard Drives:
Every computer has at least one hard drive because it's the primary storage medium in computing. Hard drives work by writing and reading blocks of data magnetically to a rigid disk made of one or more platters. They are fast, reliable, and relatively inexpensive. You can install a hard drive within a computer (internally) or it can be a separate device that interfaces with your computer over a USB, serial, or Fire Wire port.
Hard drives are ideal for online storage but because data on them is susceptible to user error, malicious attack, and occasionally device failure, they should not be the sole form of backup for important data.
CD-R, DVD-R, CD-RW, and DVD-RW Discs:
Unlike standard CD and DVD discs, you can write to a CD-R or DVD-R disc. They can hold a significant amount of data. A DVD-R disc holds up to 4.5GB. Individual discs are inexpensive and easy to store securely. A CD-R or DVD-R drive "burns" a disc by using a laser to alter the reflectivity of a dye layer, creating pits that a CD or DVD drive can read. The different capacity is achieved by narrowing the pitch or distance between tracks on the disc.
You can rewrite and reuse CD-RW and DVD-RW discs. The "RW" stands for rewritable and requires a CD-R drive to write. Older CD-ROM drives cannot read CD-RW discs because the reflectivity is lower than CD and CD-R discs. Theoretically, you can rewrite a CD-RW disc up to 1,000 times.
Magnetic Tapes:
There are many different magnetic tape solutions available today. Computers have utilized magnetic tape for storage for over 50 years, starting with big half-inch open reels and now with small removable cartridges. The tape is made of flexible plastic with a magnetic material one side and comes in many different sizes.
Magnetic tapes store data sequentially along the length of the tape. This means that to access different bits of data, a tape drive must rewind or advance the tape to find the requested files. Because of this, magnetic tapes are extremely slow compared to ati other storage media. Magnetic tape is also susceptible to damage from head crashes and magnetic fields.