Introducing the Backup Utility
The backup utility in Windows Server 2003, commonly referred to by its executable name, Ntbackup, can be opened by clicking Backup in the Accessories–System Tools program group in the Start menu. Alternatively, it can be launched by typing ntbackup.exe in the Run dialog box.
The first time you launch the backup utility, it runs in Wizard mode, as shown in below Figure. This topic focuses on the more commonly used Backup Utility interface. If you agree with most administrators that it is easier to use the standard utility than the wizard, clear the Always Start In Wizard Mode check box, and then click Advanced Mode.
As you can see on the utility’s Welcome tab in below Figure, you can back up data manually (the Backup tab) or using the Backup Wizard. You can also schedule unattended backup jobs. The Backup Utility is also used to restore data manually (the Restore And Manage Media tab) or using the Restore Wizard. The Automated System Recovery (ASR) Wizard, which backs up critical operating system files, will be discussed later in this book.
Selecting Files to Back Up
You may use the Backup tab to select the files and folders to be backed up. Items may be on local volumes or in network folders. When you select an entire folder for backup, a blue check mark appears. If you select only certain items in a folder, the folder displays a dimmed check mark to indicate a partial backup.
To back up files or folders from remote machines, either select the items from a mapped drive or expand My Network Places. The latter is the equivalent of using a Universal Naming Convention (UNC), such as \\Server\Sharename\Path-to- resource. Although selecting files and folders through My Network Places is more cumbersome (you must navigate more levels of the interface to locate the files), it has an advantage because drive mappings are more likely to change over time than UNCs.
Selecting the Backup Destination
Windows Server 2003 allows you to create a backup job on a variety of media types: a tape drive, a removable drive such as the Iomega Jaz drive, and, most importantly, directly to file on a disk volume. If the destination is a tape, the name specified must match the name of a tape that is mounted in the tape device.
If backing up to a file, the Backup Utility creates a .bkf file in the specified location, which can be a local volume or remote folder. It is not uncommon for administrators using the Backup Utility to back up a file on each server and consolidate the resulting files on a central server, which then transfers the backups to removable media. To achieve such a consolidation, the backup destination is configured as either a UNC to a single location on a central server or a local file on each server, which is later copied to a central location.
There are two important limitations of the Backup Utility. First, it does not support writable DVD and CD formats. To work around this limitation, back up to a file, then transfer the file to CD or DVD. Second, backing up to any destination except a file requires that the target media be in a device physically attached to the system. This means, for example, that you cannot back up data to a tape drive attached to a remote server.
Determining a Backup Strategy
After selecting the files to back up and specifying the backup destination, there is at least one more critical choice to make. Click Start Backup, then click Advanced, and the Advanced Backup Options dialog box appears, allowing you to specify the backup type. The backup type determines which of your selected files is in fact transferred to the destination media.
Each backup type relates in one way or another to an attribute maintained by every file: archive. The archive (A) attribute is a flag that is set when a file has been created or changed. To reduce the size and duration of backup jobs, most backup types will only transfer to media the files that have their archive attribute set. The most common source of confusion regarding the archive attribute arises from terminology. You will frequently hear, “The file is marked as backed up,” which really means that the archive attribute is cleared after a particular backup job. The next job will not transfer that file to media. If the file is modified, however, the archive attribute will again be set, and the file will be transferred at the next backup.
Normal Backups
All selected files and folders are backed up. The archive attribute is cleared. A Normal backup does not use the archive attribute to determine which files to back up; all selected items are transferred to the destination media. Every backup strategy begins with a Normal backup that essentially creates a baseline, capturing all files in the backup job.
Normal backups are the most time-consuming and require the most storage capacity of any backup type. However, because they generate a complete backup, normal back-ups are the most efficient type from which to restore a system. You do not need to restore multiple jobs. Normal backups clear the archive attribute from all selected files.
Incremental Backups
Selected files with the archive attribute set are backed up. The archive attribute is cleared. Selected files with the archive flag are transferred to the destination media, and the flag is cleared. If you perform an incremental backup one day after a normal backup has been performed, the job will contain only the files that were created or changed during that day. Similarly, if you perform an incremental backup one day after another incremental backup, the job will contain only the files that were created or changed during that day.
Incremental backups are the fastest and smallest type of backup. However they are less efficient as a restore set, because you must restore the normal backup and then restore, in order of creation, each subsequent incremental backup.
Differential Backups
Selected files with the archive attribute set are backed up. The archive attribute is not cleared. Because a differential backup uses the archive attribute, the job includes only files that have been created or changed since the last normal or incremental backup. A differential backup does not clear the archive attribute; therefore, if you perform differential backups two days in a row, the second job will include all the files in the first backup, as well as any files that were created or changed during the second day. As a result, differential backups tend to be larger and more time-consuming than incremental backups, but less so than normal backups.
Differential backups are significantly more efficient than incremental backups as a restore set, however. To fully restore a system you would restore the normal backup and the most recent differential backup.
Copy Backups
All selected files and folders are backed up. Copy neither uses nor clears the archive attribute. Copy backups are not used for typical or scheduled backups. Instead, copy backups are useful to move data between systems or to create an archival copy of data at a point in time without disrupting standard backup procedures.
Daily Backups
All selected files and folders that have changed during the day are backed up, based on the files’ modify date. The archive attribute is neither used nor cleared. If you want to back up all files and folders that change during the day without affecting a backup schedule, use a daily backup.
Combining Backup Types
Although creating a normal backup every night ensures that a server can be restored from a single job the next day, a normal backup may take too much time to create, per-haps causing the overnight job to last well into the morning, thus disrupting performance during working hours. To create an optimal backup strategy, you must take into account the time and size of the backup job, as well as the time required to restore a system in the event of failure. Two common solutions are:
■Normal and differential backups: On Sunday a normal backup is performed, and on Monday through Friday nights, differential backups are performed. Differential backups do not clear the archive attribute, which means that each backup includes all changes since Sunday. If data becomes corrupt on Friday, you only need to restore the normal backup from Sunday and the differential backup from Thursday. This strategy takes more time to back up, particularly if data changes frequently, but is easier and faster to restore, because the backup set is on fewer disks or tapes.
■Normal and incremental backups: On Sunday a normal backup is performed, and on Monday through Friday incremental backups are performed. Incremental backups clear the archive attribute, which means that each backup includes only the files that changed since the previous backup. If data becomes corrupt on Friday, you need to restore the normal backup from Sunday and each of the incremental backups, from Monday through Friday. This strategy takes less time to back up but more time to restore.
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