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To effectively back up a network, you must plan your approach to this complex task. Backups are more complicated than simply putting a tape in the drive and starting up the software. Your backup strategy should address all the following questions:
How much data do you have to back up?
How much time do you have to perform backups?
How often should you back up the data?
Who is going to be responsible for seeing that backups are completed?
How many tapes (or other media) do you plan to use?
Even if you use a fairly simple and straightforward tape rotation schedule, you’ll want to spend some time answering each of these questions to make sure your strategy answers them appropriately for your environment.
How much data With Windows Small Business Server, the standard backup strategy backs up all the files on your server. Make sure that you plan for the amount of growth you expect when you decide what backup hardware to use. Ideally, you want a tape type that will store all your files on a single tape. Or, if that’s not possible, you’ll need to buy a tape library that holds several tapes and can automatically change tapes as needed.
How much time The total amount of data you need to back up, divided by the effective backup speed your backup device can support, yields the total time your backup will take. Ideally the backup should happen during a relatively quiet time on your network to reduce the overall load on the network and your server. Different tape technologies yield different speeds, but also have different costs. Balance your need for speed with your aversion to spending money to get the best tape drive you can afford.
How often This is simple, really. How much data can you and your business afford to lose? In the event of the death of a server, you’ll need to restore from your most recent backup onto your new server. If the last time you did a backup was a week ago, you’ve just lost a week’s worth of work. Realistically, most businesses should plan on a daily backup.
Who Who is responsible for doing backups? And more importantly, who is responsible when that person is out sick, on vacation, or out of town? Don’t count on a single person being the only one who is responsible. Make sure that at least one other person knows the routine for changing tapes and handling the offsite backup plan, and so on.
How many tapes This will depend on how often you overwrite your tapes, and how many days are in your rotation. We’ll go over some more details in the next section, “Backup Schedules.”
It sometimes seems like there are as many different backup schedules as there are system administrators, but it really isn’t quite that complicated. Your backup schedule should meet the needs of your company for data protection and disaster recovery, but should also recognize the reality of the resources available.
For most businesses, a full daily backup is the core of their backup schedule. Once a week you should plan on archiving your backup tape—that is, removing it from the daily rotation and storing it someplace safe.
Why once a day? Because most businesses can’t really afford to lose more than a day or two’s worth of work. In the event of a disaster, you might need to restore your most current backup, or even the one before that if there are problems. If you’re comfortable with losing up to a week’s work, you could do once-a-week backups. But if there’s a problem with that most recent tape, you’ve lost two week’s work.
Magnetic tape is a reusable medium. You can write on it repeatedly, and read it repeatedly without noticeable problem, up to the limits of the particular type of tape. Each type of tape has an expected life span. Most system administrators plan on throwing away their tapes at about half that life span. Nothing is more frustrating when you’re in the middle of trying to restore a file or a whole directory than discovering that your backup has failed and you have to go to an earlier tape.
For most scenarios, a simple tape rotation of individual tapes for each day of the week, with a once-a-week archive tape, makes a reasonable compromise between simplicity and security. In this scenario you have a “Monday” tape, a “Tuesday” tape, and so on. Each week you put the Monday tape in the drive on Monday morning when you pull out the previous tape. Then on Tuesday morning, when you come in, you swap the Monday tape for Tuesday.
Whereas this simple one-week rotation is adequate for many scenarios, many businesses use a two-week or four-week rotation. This has the advantage of making it easier to keep the most current tapes readily available while still having an off-site archive set that is only a week old.
In addition to maintaining a daily backup, it is important to keep archival and off-site backups that allow you to recover in the event of a total disaster, or to recover to a point in time. You might well have legal requirements that require you to keep archival tapes also.
Why off-site storage? Well, if your business burns down, or is damaged by a hurricane or earthquake, it’s a real mess. But if your only backup copies are in the burned-out server room, it’s a disaster. There are commercial services that will pick up your backup tapes weekly (or as often as you want) and store them in a secure facility. They’re not inexpensive, but they do provide a reliable, secure, and predictable service.
Off-site storage is an essential part of any backup and recovery strategy. If your business really can’t afford to use a commercial off-site storage service, you can get some of the same benefits by simply having someone take the archive tape home every week. It’s not as good as having it in a secure storage facility, but it does protect from the most common disasters. It is essential, however, that you treat this as a serious responsibility and standardize how it is done if you’re to be able to depend on it in an emergency.
Which tape should you send off-site? Well, not yesterday’s! That’s the one you’re most likely to need, and need in a hurry. If your pickup day for tapes is Wednesday, send off the Wednesday tape, and put a new tape in your rotation on Wednesday. Keep at least a month’s worth of weekly backups off-site, and then have them bring back the tape from a month ago, and put it back into your rotation.
Windows Small Business Server enables Volume Shadow Copy automatically on the drive that houses the Users share and sets save points or snapshots twice a day. You can enable Volume Shadow Copy on additional volumes as appropriate to your business. This allows users to quickly recover to a previous version of a lost, damaged, or deleted file without administrative involvement and without having to load up yesterday’s backup tape and restore it.
If you have the disk space, and your comfort window for lost data is not very high, you can increase the frequency of scheduled snapshots to more often than twice a day. Keep in mind, however, that disk space is finite. For most situations, the default setting of twice a day is sufficient.
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For more information about enabling and configuring volume shadow copies, see Chapter 8, “Storage Management.”
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