Chapter 6 - Backing Up and Restoring Network Files

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Regular backup of servers and local hard disks prevents data loss and damage caused by disk-drive failures, power outages, virus infection, and other potential network disasters. Backup operations based on careful planning and reliable equipment make file recovery a relatively painless process.

Windows NT includes the Backup program — a graphical tool that enables you to use a tape drive to back up and restore important files on either Windows NT file system (NTFS) or file allocation table (FAT) partitions. The Backup program also simplifies archiving. You can easily save data for legal or historical purposes and to remove older, unused files, safe in the knowledge that you can recover them if necessary.

The first section of this chapter, "Forming a Network Backup Plan," describes general strategies for setting up a tape backup system on your network. The remainder of the chapter describes how to use the Backup program to perform backup and restoration operations.

Additional data protection measures, such as fault tolerance and uninterruptible power supplies (UPS), are covered in Chapter 7, "Protecting Data," and in the Windows NT Server Resource Kit version 4.0.

On This Page

Forming a Network Backup Plan
Backing Up Disk Files to Tape
Using Windows NT Backup
Windows NT Backup Command Prompt Parameters
Maintaining Tapes
Restoring Tape Files to Disk
Backup Example

Forming a Network Backup Plan

Network backup plans are most effective when they are based on both system needs and a strategy. As you formulate a tape-backup plan, you must consider the following questions:

• Which backup strategy is best suited to my environment?

• What hardware does the strategy require?

• What is the best location for a tape drive?

Strategic Considerations

Which of the following backup strategies is best suited to your environment? (If you are not sure, examine the advantages and disadvantages in the tables immediately following the list.)

• Server only or network backup. Do you plan to back up your entire network, with tapes drives attached only to certain servers where users copy their important files?

• Individual or local workstation backup. Will each workstation/user have a tape drive and be responsible for backing up his or her computer?

• Server and workstation backup. Will one individual be responsible for backing up computers for a group? (For example, will there be one tape drive for the accounting department and another for the legal department?)

Server-Only Backup

Advantages	Disadvantages
Fewer tape drives needed.	Registries and event logs of remote computers are not backed up.
Less media to manage because more backups are stored on tape.	Backups and restorations are slower due to network throughput limitations.
Depending on the size of your network, server-only backup can be less expensive than backing up each workstation individually.	Backups and restorations require greater planning and preparation. They must be scheduled when network traffic is at a minimum or when critical information can be backed up as quickly as possible.

Local Workstation Backup

Advantages	Disadvantages
Fewer network resources committed to a lengthy backup procedure	Using more tape drives is more expensive
Quicker file recovery.

Server and workstation backup combines the advantages and disadvantages of server only and local workstation backups.

Hardware Considerations

The most common medium for backups and the one used by Windows NT Backup is magnetic tape. Tape is popular because it offers great capacity at low cost. The primary tape drive types used for backup include quarter-inch cartridge (QIC), digital audio tape (DAT), and 8-mm cassette. High-capacity, high-performance tape drives generally use small computer system interface (SCSI) controllers. For information about supported tape drives, see the Windows NT Server Hardware Compatibility List.

Tape technology changes rapidly, so it is best to research the relative merits of each type of medium before purchasing. When selecting a tape drive, consider drive and media cost, as well as reliability and capacity. Ideally, a tape drive should have more than enough capacity to back up your largest server. It should also provide error detection and correction during backup and restore operations.

How Many Tape Drives Do You Need?

The number of drives you need depends on your overall backup strategy. Because tape cartridges are available in sizes greater than 5 gigabytes, you can probably back up your entire network with a few tapes and a single high-speed drive. However, the recent availability of less expensive tape drives makes individual workstation backups a sound option, too.

Location Considerations

You can cable your tape drive to either a workstation or to a server. There are advantages and disadvantages to either configuration:

• If you run backups from a server, you can back up and restore that server very quickly because your backups include the server's registry. On the other hand, if your network has more than one server, the speed advantage is lost.

• Servers typically operate 24 hours a day and are logical candidates to run backups during off hours. However, if a problem with backup hardware occurs, you might have to power down your server.

• As a general rule, though, if most of your information is on one server, you are better off running backups from that server.

Whether you run remote backups from a workstation or a server, it makes sense to place a tape drive on the portion of your network with the greatest bandwidth (highest transmission frequency). You might also consider placing the tape drive in a secured room for data security.

Backing Up Disk Files to Tape

Because information is the most important resource on a computer or network, information backup and retrieval are an administrator's most critical functions. Plus, it is important to create backup policies and standard hardware-maintenance policies to avoid problems rather than just recover from them. You must consider the following questions when developing such policies:

• Which backup procedure is most appropriate?

• How often should backup occur?

• Where is the best place to store tapes?

The answers will determine the steps you take to protect critical data. Such steps can range from a simple backup done with the Windows NT Backup program to the use of disk fault-tolerance methods. Then decide how often you need to repeat a complete risk assessment. You will need to evaluate the continuing importance of various operations and determine likely new areas of exposure.

Note: The Windows NT Server Disk Administrator program provides fault-tolerance functionality for creating mirror sets and stripe sets with parity. For more information about Disk Administrator, see Chapter 7, "Protecting Data."

Types of Backup

There are five types of backup: normal, copy, incremental, differential, and daily. The most common types are normal (full), incremental, and differential.

• A normal backup copies all selected files and marks each as having been backed up. With normal backups, you can restore files quickly because files on the last tape are the most current.

• A copy backup copies all selected files but does not mark each file as having been backed up. Copying is useful if you want to backup files between normal and incremental backups because copying does not invalidate these other backup operations.

• An incremental backup backs up only those files created or changed since the last normal or incremental backup. It marks files as having been backed up. If you use a combination of normal and incremental backups, restoring requires starting with your last normal backup and then working through all the incremental tapes.

• A differential backup copies those files created or changed since the last normal (or incremental) backup. It does not mark files as having been backed up. If you are doing normal and differential backups, restoring requires only the last normal and last differential backup tape.

• A daily backup copies all selected files that have been modified the day the daily backup is performed. The backed up files are not marked as having been backed up. (This can be useful if you want to take work home and need a quick way to select the files that you worked on that day.)

The following table lists advantages and disadvantages associated with running the most common types of backup.

Backup type	Advantages	Disadvantages
Normal	Files are easy to find because they are always on a current backup of your system or on one tape or tape set.	Most time-consuming.
	Recovery requires only one tape or tape set.	If files do not change frequently, backups are redundant.
Incremental	Least data storage space required.	Files difficult to find because they can be on several tapes.
	Least time-consuming.
Differential	Less time-consuming than normal backups.	Recovery takes longer than if files were on single tape.
	Recovery requires only the last normal backup tape and last differential tape.	If large amounts of data change daily, backups can be more time consuming than incremental.

Note: Perform regular backups when the fewest people are using the network. If many files are in use, the backup might not accurately reflect your network.

How Often to Back Up

Although it is best to have three copies of important data to protect against tape failure or loss, the frequency with which you create these back ups depends on how often your data changes and on its value to you. Backups can consist of a weekly, a monthly, and an archive backup. The archive tape can be a simple copy rather than a complete backup.

Note: Backups are also a protection against virus contamination. Because some viruses take weeks to appear, keep normal backup tapes for a month or more to ensure that you can restore a system to its preinfection status.

Alternating Tapes

By alternating backup tapes you lower the backup cost. The following sections describe a 12-week and a one-year sample tape-alternation schedule. The life cycle of a tape depends on the manufacturer and storage conditions.

Backing Up Over 12 Weeks

The 12-week schedule uses a different backup tape each day for two weeks, and then the first tape is used again at the beginning of each third week. Incremental backups are performed Monday through Thursday after an initial normal backup. Normal backups are performed on Fridays with the most recent normal backup stored on-site. The normal backup of the preceding week is stored off-site. At the end of the 12 weeks, the cycle starts over with a new set of tapes.

Backing Up Over One Year

One popular tape-alternation schedule uses 19 tapes over the course of one year Four tapes are used Monday through Thursday for incremental (or differential) backups, and three tapes are used for weekly normal backups (performed each Friday). The remaining 12 tapes are used for monthly normal backups and are stored off-site.

Verifying Backups

A verify operation compares files on disk to files that have been written to tape. It occurs after all files are backed up or restored and takes about as long as the backup procedure itself. It is a good idea to perform a verify operation after every backup. If you are backing up to a set of tapes that will be stored for a long time, it is wise to verify them. Verifying after file recovery is also recommended.

Note: If a verify procedure fails for a given file, check to see when that file was last modified. If someone changes a file between a backup and verify operation, the verify procedure fails.

Storing Backup Tapes

You must find an off-site location for storage of backup and archive tapes. The location can be a vault or other place that can protect the tapes from fire, water, theft, and other hazards. If you use a fireproof safe, make sure it is specifically designed to protect magnetic media.

Tapes last longer in cool, humidity-controlled locations. Your storage area should also be free of magnetic fields, such as those found near the backs of computer terminals and analog telephones.

Documenting Backup Operations

Accurate backup records are essential to finding missing information quickly, particularly if you have accumulated large numbers of high-volume tapes. Records can include tape labels which should be accompanied by a log book, catalogs, and log files.

Tape Labels

Tape labels should contain a date, the type of backup (normal, incremental, or differential), and complete information regarding tape contents. Indicating the type of backup is important. If you are restoring from differential or incremental backup tapes, you need to locate the last normal backup tape and either the last differential tape or all incremental tapes created since the last normal backup. Alternatively, you can label tapes sequentially and keep a log book of tape contents.

Catalogs

Most backup software include a mechanism for cataloging backup files. Windows NT Backup stores backup catalogs on tape, temporarily loading them into memory during program sessions. Catalogs are created for each backup set (a collection of files from one drive that is backed up). Catalogs cannot be printed or saved to disk.

Log Files

In addition to an online catalog, all operation information can be logged to a file. The log file can include the names of all files and directories successfully backed up and restored. For information about how to log backup operations, see "Setting the Log Options" in Backup Help.

Using Windows NT Backup

The Windows NT Backup program is located in the Administrative Tools folder.

The following list describes how you can use the Backup program to protect data:

• Back up and restore both local and remote files on an NTFS or a FAT partition from your own computer using an attached tape drive.

• Select files for backing up or restoring by volume, directory, or individual file name, and view detailed file information, such as size or modification date.

• Select the verification pass option to ensure reliable backups or restorations.

• Perform any of the following common types of backup operations: normal, copy, incremental, differential, and daily.

• Place multiple backup sets on a tape, and either append new backup sets or overwrite the whole tape with the new ones.

• Span multiple tapes with both backup sets and files because there is no file-size restriction.

• Create a batch file to automate repeated backups of drives.

• Review a full catalog of backup sets and individual file and directory information so you can select files to be restored.

• Control a restore operation's destination drive and directory.

• Save log information about tape operations to a file. Also view tape-operation information in Event Viewer.

Selecting Hardware

The system automatically checks for a tape drive when you start Windows NT and initializes the hardware each time you start Backup. The tape drive must be cabled to the computer where the program is run. Notice, however, that to ensure the drivers load properly, the tape drive must be turned on before you start Windows NT. If you have more than one tape backup device, use the Hardware Setup command from the Operations menu to select a different device.

Note: If you do not have a tape drive, you can use the backup or xcopy commands to back up files to a floppy disk.

Windows NT currently supports both high-capacity SCSI tape backup devices for 4 mm DAT, 8 mm, and .25-inch drives and the less expensive mini-cartridge drives. You can have more than one tape drive cabled to your system. However, only one tape drive can be selected at a time. For more information about supported tape drives, see the Windows NT Server Hardware Compatibility List.

Inserting a higher-density tape than the tape drive is capable of using can cause the program to display "Tape Drive Error Detected" and prevent the tape from being ejected until you close Backup.

Note: Only programs that support the Microsoft tape format can create Windows NT-compatible tapes.

Backing Up Other Operating Systems

You can use the Backup program to back up any computers to which you can connect remotely. Windows NT Backup does not recognize MS-DOS or Windows 3.1 workstations.

Note: Windows NT Backup cannot back up Registries or event log files on remote computers.

Before running the program, each computer you want to back up must be established as a logical drive (D, E, F, and so on) on the computer that the tape drive is connected to. Typically, you would incorporate logical drive connections into the batch file you use to run your backups.

Backup Menu Commands

Click the Backup folder in the Administrative Tools (Common) folder to display the main Backup window with the Drives window open and a minimized Tapes window. (You can also type ntbackup or start ntbackup at the command prompt.)

Each time you start Backup, the program scans for and detects new or additional tape drives. If a new drive is detected, you are prompted to use the Tape Devices option in Control Panel to install the driver.

For information about how to load a tape driver, see "Loading a Tape Driver" in Help.

The following most commonly used commands from the Operations and Select menus are also available on the toolbar.

Backup	Retention Tape	Check
Restore	Eject Tape	Unchecked
Catalog	Erase Tape

The Tree, View, and Window menus provide commands for manipulating your windows the same as in the Windows NT Explorer. The View menu also enables you to display or hide the status bar and toolbar and to change your font selection. For more information about Backup menu commands, see Backup Help .

Choosing Files to Back Up

You can specify which files to back up. To specify all files, click the Check button on the toolbar. To select individual files, select the check box for each file name.

The Drives window is normally open when you start the Backup program.

If you connect to another network drive while using Backup, choose Refresh from the Window menu to update the Drives window and view the additional network drive.

For information about how to select files to backup, see "Backing up all the Files" or "Backing up Individual Files" in Help.

Note: When a disk drive is selected, the program will not back up those files and directories that the user does not have security permission to read. Hidden files with read permission will be backed up and are displayed with an exclamation point in the file's icon. During Backup, all file attributes, including permissions, are preserved.

Files That Are Not Backed Up

Windows NT Backup does not indiscriminately backup and restore all files. Instead, it follows rules that protect system security and data integrity.

The following file types are not automatically backed up when you run Windows NT Backup:

• Files you do not have permission to read. Only persons with backup rights can copy files they do not own.

• Paging files. (These are temporary files used to represent virtual address space.)

• Registries on remote computers. Windows NT backs up only the local registry.

• Files exclusively locked by application software. Windows NT Backup cannot copy files locked by application software. However, it supports backup of all files that are part of the operating system. Windows NT locks two types of files: event logs and registry files.

If Windows NT Backup encounters a file that is open in share/read mode, it backs up the last saved version of the file.

For information about backing up registries on remote computers, see the Windows NT Workstation Resource Kit version 4.0.

Setting Tape Options

After selecting one or more disk drives or files to back up, click the Backup button to open the Backup Information dialog box. The upper section provides information about the tape that you loaded and enables you to specify backup options. The lower section displays information about the backupset and enables you to create a log file of the backup.

The following table describes the options in the upper section of the Backup Information dialog box. For more information about the lower section of the dialog box, see the sections that follow the table.

Item	Description
Current Tape	The current tape's name is shown here unless there is no tape loaded, it is blank, or it has an unrecognized format.
Creation Date	The creation date of the original backup set or the date when it was last replaced is automatically displayed here.
Owner	The owner of the tape, that is, whoever put the first backup set on the tape, is automatically displayed here.
Tape Name	You can use up to 32 characters to create or change a current tape name.
Append	This operation adds the backup sets to the end of the last backup set on the active tape. Tape Name and Restrict Access To Owner Or Administrator are unavailable with this operation.
Replace	This operation overwrites all the information on the tape. However, if you do not confirm the choice, another message gives you the option of appending instead.
Verify After Backup	You can specify whether or not to perform a verification comparison of the files that are written to tape and the files on the disks.
Restrict Access To Owner Or Administrator	You can designate the tape as "secure." Only the tape owner or a member of the Administrators or Backup Operators group can read, write, or erase the tape using the Windows NT Backup program. To restore it on another computer in the same domain, you must be logged on with the same user account name for that domain. Members of the Administrators or Backup Operators group can read, write, or erase a tape on any computer and in any domain.
Hardware Compression1	You can request that the tape drive compress the data onto the tape media. However, do not select this option if you want to move this tape later to another tape drive that does not support hardware compression. This option is available only if the tape drive supports selectable hardware compression.
Backup Local Registry	You can include a copy of the local Windows NT Registry files in the backup set. This option is available only if the drive containing the registry is selected. Windows NT Backup does not back up configuration information or event logs located on remote computers.
1 Keep in mind, however, that moving tapes between different brands of tape drives can cause problems if one brand supports compression and the other one does not. Depending on the tape drive, the program could display messages such as "Tape Drive Error Detected," "Tape Drive Not Responding," or "Bad Tape." To erase a tape that is causing one of these problems, start Windows NT Backup from the command prompt with the /nopoll parameter. However, be careful not to use Backup with the /nopoll parameter to perform anything other than erasing the tape.

Granting Backup and Restore Privileges

In Windows NT, file access is limited by NTFS file permissions (No Access, List, Read, Add, Add and Read, Change, Full Control, Special Directory Access, Special File Access), share permissions (No Access, Read, Change, Full Control), and file attributes (Read Only, Hidden, System). FAT does not provide file permissions.

However, the permissions and attributes can be overridden if you are granted certain user rights in User Manager for Domains. Two of the user rights, Backup files and directories and Restore files and directories, are used by the Backup program to enable you to backup or restore regardless of the permissions or attributes set on the files.

If the rights are not granted, you cannot backup or restore files and directories that you do not have access to unless you are a member of the Administrators or Backup Operators group. The Administrators and Backup Operators groups are granted these rights by default.

Backup and restore rights are independent of each other. However, it is recommended that backup rights be granted along with the restore rights. Use caution in granting restore rights because normal file-permission conflicts are ignored during restoration and existing files can be overwritten.

Reserve backup and/or restore rights for those few individuals who have regular responsibility for backing up your network. Large sites might want to create two groups of backup operators: one with only backup rights; the other with backup and restore rights.

For more information about user rights and groups, see Chapter 2, "Working with User and Group Accounts."

Setting the Backup Set Information

The second section of the Backup Information dialog box shows how many backup sets have been selected. If you select multiple disk drives, Backup provides a scroll bar for moving between backup sets so that you can enter separate descriptions (up to a length of 32 characters) and select different backup types for each.

When deciding which backup type to use, one of the criteria should be whether or not it will mark the files as having been backed up. Windows NT maintains a marker (called the archive bit) for each file that allows backup programs to mark the files after backing them up. When the file changes, Windows NT marks the file as needing to be backed up again.

With Windows NT Backup, you choose to back up only those files that have this marker set, and you choose whether or not to mark files as having been backed up.

• The normal (or full) backup type is best when a large amount of data changes between backups or to provide a baseline for the other backup types.

• The incremental backup type is good if you need to record the progression of frequently changed data. The differential backup type simplifies the process for restoring files.

• To provide for long-term storage with fewer tapes, you can use a combination of a normal backup plus either incremental or differential backups.

For more information about types of backup, see the "Types of Backup" section earlier in this chapter.

Setting Log Options for Backup and Restore

In the bottom section of the Backup Information and the Restore Information dialog boxes, you can specify not to log information or to create a log that contains either a summary of major operations or full details on all operations.

Select	To
Full Detail	Log all operations information including the names of all files and directories that are backed up.
Summary Only	Log only major operations such as loading a tape, starting the backup, and failing to open a file.
Don't Log	Log no information.

How Windows NT Backup Keeps Track of Files

Each tape used for backup can consist of several backup sessions or sets. At the end of each backup set, Windows NT Backup stores a summary of file and/or directory information in a backup set catalog. At the end of each tape is a backup set map that maintains the exact tape location of the backup set's data and catalog. This information is temporarily cached from tape to disk when you run the Backup program.

Windows NT Backup Command Prompt Parameters

Backup operations can also be performed at the command prompt using the ntbackup command. Most of the command's parameters do not require user input and can therefore be implemented in batch files. However, a few of the parameters require user input.

The following parameters require user input:

Syntax

ntbackup [/nopoll] [/missingtape]

/nopoll

Specifies that the tape should be erased.

Caution: Do not use /nopoll with any other parameters.

/missingtape

Specifies that a tape is missing from the backup set when the set spans several tapes. Each tape becomes a single unit as opposed to being part of the set. For more information about the missingtape parameter, see "Building Partial Tape and Backup Set Catalogs" later in this chapter.

You can create a batch file to back up one or more drives regularly. However, using batch files enables you to back up directories only (not individual files). Also, wildcard characters cannot be used in the batch files.

The following parameters do not require user input and are useful in batch files.

Syntax

ntbackup operation path [ /a ][ /v ][ /r ][ /d " text " ][ /b ][ /hc: { on | off }] [ /t { option }][ /l " filename " ][ /e ][/ tape: { n }]

Parameters

operation

Specifies the operation, backup or eject.

Note: Each of the following parameters, with the exception of /tape must be used only with the backup operation parameter. path

Specifies one or more paths of the directories to be backed up.

/ a

Causes backup sets to be added or appended after the last backup set on the tape. When /a is not specified, the program overwrites previous data. When more than one drive is specified but /a is not, the program overwrites the contents of the tape with the information from the first drive selected and then appends the backup sets for the remaining drives.

/ v

Verifies the operation.

/ r

Restricts access. The /r parameter is ignored if /a is also specified.

/ d " text "

Specifies a description of the backup contents.

/ b

Specifies that the local registry be backed up.

/ hc:on or /hc:off

Specifies that hardware compression is on or off.

/ t { option }

Specifies the backup type. Option can be one of the following:

normal	copy
incremental	differential
daily

For more information about the types of backup, see "Types of Backup" earlier in this chapter.

/l " filename "

Specifies the file name for the backup log.

/e

Specifies that the backup log include exceptions only.

/tape:{n}

Specifies the tape drive to which the files should be backed up. N is a number from 0 to 9 that corresponds to the number the drive was assigned when the tape drive was installed.

Examples Using Backup from the Command Prompt

When the append (/a) parameter is not specified in a backup batch file, the Backup program overwrites the tape contents. Specifying append causes backup sets to be added after the last backup set on the tape. When more than one drive is specified in the batch file and the append parameter is not, the program overwrites the contents of the tape with the information from the first drive selected and then appends the backup sets for the remaining drives.

Three of the following examples show how to implement the append (\a) parameter.

Example 1

This example shows you how to perform the following activities:

• Perform a normal backup of drives C, D, and E.

• Restrict access to the owner or administrator.

• Apply the description "Full Backup of drives C, D, and E" to all three backup sets.

• Perform a verification pass upon completion of the backup.

• Record the results of the session in the log file named C:\LOG\LOG.TXT.

To do this, type the following at the command prompt:

NTBackup Backup C: D: E: /t Normal /v /r /d "Full Backup of drives C, D, and E" /l "C:\LOG\LOG.TXT"

Example 2

This example shows you how to perform the following activities:

• Perform a copy backup of the files in C:\EXCEL\PERSONAL.

• Do not restrict access.

• Use the description "Copy of Personal Excel Directory."

• Perform a verification pass upon completion of the backup.

• Record the results of the session in the log file named C:\LOG.TXT.

• Write the backup to tape drive number 1, which is the second tape drive.

To do this, type the following at the command prompt:

NTBackup Backup C:\EXCEL\PERSONAL /t Copy /v /d "Copy of Personal Excel Directory
" /l "C:\LOG.TXT" /tape:1

Example 3

This example shows you how to perform the following activities:

• Perform an incremental-type backup of drives C, D, E, and the registry.

• Have the tape drive compress the data on the tape.

• Apply the description "Compressed Incremental Backup of drives C, D, and E including Registry."

• Perform a verification pass upon completion of the backup.

• Record the results of the session in the log file named C:\WEEKLY.LOG.

To do this, type the following at the command prompt:

NTBackup Backup C: D: E: /t Incremental /b /hc:on /v /d 	 
"Compressed Incremental Backup of drives C, D, and E 	 
including Registry" /l "C:\WEEKLY.LOG"

Example 4

This example shows you how to eject a tape from drive one.

To do this, type the following at the command prompt:

NTBackup Eject /tape:1

Maintaining Tapes

The Windows NT Backup program provides three commands on the Operations menu to help you maintain your backup tapes: Erase Tape, Retension Tape, and Format Tape.

Erase Tape

The Erase Tape command erases the entire tape. A warning message in the Erase Tape dialog box advises that all information on the tape will be destroyed. It also provides the name of the tape and its date of creation.

You can do either a Quick Erase (rewrite the tape header) or a Secure Erase (overwrite the entire tape). A Secure Erase can take several hours to complete, depending on the drive technology and tape length. Categorize the information on the backup tapes by which method of erasing to use, and then create and maintain a list for easy reference.

Retension Tape

The Retension Tape command eliminates loose spots on the tape by fast forwarding to the end of the tape and then rewinding. This procedure winds the tape evenly so it will run more smoothly past the tape drive heads.

To reduce tape slippage, manufacturers of tape backup drives recommend that you retension .25-inch tape once every 20 uses. Note that 4 mm and 8 mm tapes do not require retensioning, and so the command is unavailable. The time required to forward and rewind media depends on the device technology. For specific retensioning requirements, see the manufacturer's documentation.

Format Tape

The Format Tape command formats an unformatted minicartridge tape. This type of tape must be formatted before it can be used. If you do not have a minicartridge drive installed and activated, this command is unavailable.

Restoring Tape Files to Disk

Backed-up information is useless if it cannot be restored. Windows NT provides a Restore command to give access to tapes, backup sets, and files for restoring as they are needed.

Restoration policies for everyday maintenance, not to mention for emergency recovery, are as important as backup policies. Practice ahead of time on spare drives, though, so you do not risk overwriting real data. You should also periodically do trial restorations to check whether files have been backed up properly. Such trials check for possible hardware problems that do not show up with the software or whose symptoms are not easily recognized. For that reason, keep a backup status log, and check it regularly for error messages.

When restoring a large number of files, you should consider what backup you used. If you did differential or incremental backups, first restore the selected files from the most recent normal backup, then files from all subsequent incremental backups of those files, and finally the most recent differential backup performed after the last incremental backup.

For tape-management purposes, the following information is associated with each tape:

• A user-specified tape name

• An original tape-creation date plus the date and time that each backup set was created

• The computer name and the user name of the user who created the tape

• A tape-sequence number in the case of tape sets

Choosing What You Want to Restore

You can restore the current tape, one or more backup sets, or individual files. Open the Tapes window and make your selections the same way you would for backing up.

All catalog information is maintained on the corresponding tape for that backup set. Family sets have the information on the last tape.

The tape name appears in the left panel of the Tapes window to the right of each tape icon. The following information is shown in the right panel of the Tapes window:

• Drive backed up

• Backup set number

• Tape number and what number it is in a set of tapes

• Backup type

• Date and time of backup

• Backup description

When you insert a tape to restore information, only information about the first backup set is displayed in the right panel until you load the tape's catalog. To restore the entire tape, you must load the tape's catalog first to display a complete list of other backup sets on the tape. Otherwise, when you select an entire tape, you are really selecting only those sets that are already displayed. To know which files are in each backup set, you must load the individual catalogs for each backup set.

For information about how to load a catalog of the backup sets, restore tapes or backup sets, and restore individual files see "Loading Catalogs," "Restoring Tapes or Backup Sets," and "Restoring Individual Files" in Backup Help.

Files That Are Not Automatically Restored

Windows NT Backup restores all files except the following:

• Tape files that are older than a disk file. If a file being restored already exists on disk, and the disk file is newer than the tape file, the Backup program asks you to confirm replacement.

• A file to be restored into a directory for which you do not have access. Likewise, if you do not have write access to a file, you cannot restore over it. These conditions do not apply if you have restore rights.

Building Partial Tape and Backup Set Catalogs

If a backup operation spans several tapes and you choose to restore a single backup set, you are prompted to insert the last tape to load the tape catalog information and receive a complete list of all the backup sets and their locations. However, if the last tape in such a family set is missing or damaged, you can force Backup to deal with the data on each remaining tape as if it were a single unit rather than a member of a family set. To do so, start Backup from the command prompt with the /missingtape parameter. However, this process will take additional time.

For information about how to build catalogs from a partial tape set, see "Building Partial Tape and Backup Set Catalogs" in Backup Help.

Restoring Files from Third-Party Backup Programs

At times you might want to restore from a tape with files that were not backed up with the Windows NT Backup program. If the tape is in the Microsoft tape format (MTF), Windows NT Backup can read it. However, be aware that the tape might not have the full on-tape catalog (OTC) information that Windows NT Backup produces. Also, some older tape backup devices may not support creating full on-tape catalogs with the Windows NT Backup program.

Setting Restore Options

After selecting one or more tapes, backup sets, or files to restore, choose the Restore command from the Operations menu to open the Restore Information dialog box. The first section provides information about the backup sets on the loaded tape and indicates the number of tapes in that family set. For each backup set, you must specify the drive to which you want the information restored.

You can also specify an alternate directory path to place a backup set's files into a different directory instead of into the original one on the default drive. This might be done to compare them to the files on the disk. The Browse button at the end of the Alternate Path box can help you find the correct path.

To compare the contents of the restored files against the files on tape and log any exceptions, select the Verify After Restore check box.

When you select the Restore File Permissions check box, the system restores the permissions information along with the file if the files are being restored to an NTFS partition. Otherwise, the files inherit the permissions information of the directory into which they are restored.

To restore Registry files, select the Restore Local Registry check box. However, you will need to restart the computer for the restored information to take effect.

File permissions (or security settings), such as ownership or access permissions, can be restored only when the restored files were backed up from an NTFS volume and restored to an NTFS volume. However, you should restore file access permissions only if you are restoring files to computers in the same domain as that of the original owner's account. For example, you could restore files to other computers in a domain if the original permissions on the files allowed access to a user account in that domain.

Note: Do not restore file permissions in the following situations:

• If you are using the backup tape to transfer files to another computer outside the original domain.

• If you are restoring files to a computer that has not been completely restored following the corruption of the operating system.

Restoring the Local Registry

Be aware of these steps before you try to restore the registry:

• After restoring the registry, you must restart your computer, which means you lose any configuration changes made since the last Registry backup.

• To restore a registry onto a new computer (if, for example, your hard drive breaks), you must first reinstall Windows NT on the new computer and then restore a full backup tape of your hard drive.

For more information about the registry, see Appendix A, "Windows NT Registry," or the Windows NT Resource Kit version 4.0.

Restoring File Security Settings

Windows NT files may have permissions, ownership, and audit flags associated with them. Windows NT Backup preserves this information on files restored to NTFS partitions but not on files restored to FAT partitions. It is not possible to secure information on FAT file systems.

When you restore files to a new computer (a new hard drive), you do not have to restore security information. (The files inherit the permissions of the directory in which they are placed.) If the directory has no permissions, the file retains its previous permissions, including ownership.

Backup Example

The following example illustrates how to backup a small network comprised of clients running different operating systems.

Setting Up a Backup Program for a Small Network

Suppose you need to back up a Windows NT Server computer and 20 client computers. The clients are a mix of computers running MS-DOS, Windows for Workgroups, Windows 95, and Windows NT. You plan to purchase one tape drive and controller card and use Windows NT Backup.

You can work out a solution by following four steps:

1. Research and select a tape drive based on reliability, speed, capacity, cost, and Windows NT compatibility. The drive should support tape cartridges with more than enough space to back up your entire server.

2. Locate your tape drive at the server so that you can back up the server registry and so that server backups take place as quickly as possible. From the server, you can back up user files on remote computers running only Windows for Workgroups, Windows 95, and Windows NT.

3. Install the tape controller card in the server, and attach the tape drive. Be sure that the tape drive is turned on before powering up the server; otherwise, the SCSI tape driver will not be loaded properly.

4. Specify a tape alteration schedule that includes backing up computers running Windows for Workgroups, Windows 95, and Windows NT Workstation. To conserve tapes, back up client computers less frequently than your server and, space permitting, encourage users to copy extremely important files to the server at the end of the day. The following illustration shows a possible rotation schedule.

Because Windows NT Backup does not back up files on MS-DOS computers, consider reserving some space on the server where MS-DOS and Windows 3.1 users can copy important files. These files would be backed up during regular server backups.