When you develop your backup plan, keep the following in mind:
Be sure you have spare hardware and cartridges on hand in case of a failure.
Test backed-up data regularly to verify the reliability of your backup procedures and equipment.
Include stress testing of backup hardware (storage drives, optical drives, and controllers) and software (backup program and device drivers).
There is a range of system configurations that can affect your backup strategies. At one end of the range is a simple, stand-alone computer with one user. At the other is a workgroup network with a computer that is hosting a network public file share.
CAUTIONBackup does not back up files on computers that are running MS-DOS. Consider reserving some space on a network share so that users of MS-DOS and Microsoft® Windows® version 3.1 can copy important files. After these files are on the network share, they can be backed up during regular file server backups.
You can work out a backup solution by following these four steps:
Research and select a device on which to record your backups. When considering new backup hardware, be sure to consider its reliability, speed, capacity, cost, and compatibility with Windows 2000. The cartridges should provide more than enough space to back up all of your data.
If necessary, install a controller card in the computer. If you choose to use a SCSI-based tape drive, put the tape drive on its own controller.
Connect your new backup drive to the computer so that you can back up the System State data. If you are using an external SCSI drive, start the drive before you start the computer so that the driver can be loaded properly.
Establish a backup cartridge rotation schedule. You need to continue making backups as long as data is created or changed.
Over a period of time, you should use several separate disks or tapes when you run your backup regimen. By using multiple disks or tapes instead of repeatedly using the same disk or tape, you gain additional benefits with your backup program:
It preserves access to multiple versions of data files in case a user needs to restore an older copy of a data file.
If the last backup fails as a result of a bad cartridge, you have a backup from the previous process.
You extend the useful life span of each cartridge.
TIPHave several extra, new, blank, formatted media available in case of cartridge failure. Regularly scan the Backup log for errors that might indicate that a backup cartridge is beginning to fail.
Be sure to clean a tape drive's recording heads regularly. Failure to do so can lead to unusable backups and the premature failure of the tape drive. See the tape drive manufacturer's recommendations for the proper method and frequency of cleaning.
You need to choose a backup medium to use. If the quantity of data that you need to backup is small, a removable hard disk or writable CD might be all that you need. However, for more flexibility and capacity for growth, tape is still the backup medium of choice.
After your tape drive is installed, decide on a backup schedule and the types of backups. If the data that is created on a daily basis is irreplaceable, daily backups are recommended. If the data is less valuable, the frequency of backups can be less often. It should be recognized, however, that the longer the period between backups, the greater the potential for loss. Just as it is unwise to work on a document all day without saving the file, it is unwise to work on a document all week with backing it up. The value of the data should help you determine the appropriate frequency of backups.
The type of backups you make determines how easy or difficult it is to restore the data in an emergency. The compromise is between security and convenience. If you choose to run full, normal backups every day, you can restore lost data easily, but the backups can take a substantial amount of time (depending upon the quantity of data to be backed up and the data transfer speed of the recording device). If you choose to make incremental backups for a month after making a full backup, you save substantial time in the backup process. However, to fully restore a corrupted hard disk, it is likely to require that you restore the normal backup, then each incremental backup in successive order. Substituting a differential backup for the incremental backup shortens the restore process, but as each day's backup process takes more time than the previous day, the total accumulation of changed files continues to grow. In addition, you can lose the ability to retrieve earlier versions of document files, unless you use separate cartridges for each differential backup.
Computers that contain frequently changing data, that contain data that is hard to replace or reproduce, or that provide a public network share should be backed up daily. Run a full, normal backup every Friday. Every Monday through Thursday run a differential backup to a different tape or disk. After the second Friday, full backup has been successfully made, put the first full backup away as a temporary archive. Then after every following Friday's full backup, alternate the full backups as temporary archives. On every eighth Friday, save the full backup as a permanent archive, which should be stored in a secure, off-site location. Over the course of a year, this method uses at least 14 tapes or disks.
NOTEIf the computer is used seven days a week, add a Saturday and Sunday differential backup to the schedule.
Use new tapes if you choose to make permanent archives on tape.
If the computer is used less often or if the data is not as valuable, consider making one incremental backup each week for three weeks and one full, normal backup every fourth week, alternating the full backups between two cartridges to ensure that at least one always exists. This reduces the amount of time spent creating backups, but it also reduces protection against data corruption or erasure. Over the course of a year this method uses at least fives tapes or disks.
The following scenario illustrates a possible approach for backing up a small network that consists of a computer that is running Windows 2000 Professional and that is hosting a public file share for 20 other client computers.
Connect a tape drive to the share host computer. From the share host computer, you can back up user files on remote computers that are running Microsoft® Windows for Workgroups, Microsoft® Windows 95, Microsoft® Windows 98, Microsoft® Windows NT®, and Microsoft® Windows 2000. (See the two suggested methods for doing this that follow.) Establish a tape rotation schedule. If conserving tapes is a requirement, back up clients less frequently than you back up the share host and encourage users to copy critical files to the network share at the end of the day.
In the descriptions of the following methods for backing up remote computers, the computer that contains the data to be backed up is called "Data." The computer that runs the backup process is called "Target."
Back up Data locally to disk. Use a networked backup or Xcopy to move the resulting backup file to Target. Make sure you run a backup verification pass that compares the data on Data and the data on Target on a regular basis. Ethernet or Token Ring transfer speeds usually are approximately 1 megabyte (MB) per second if the network is not busy. You can use this transfer rate and the total amount of data being transferred to estimate the transfer time. If the transfer time is too long, you might need to use a faster network connection or a different backup method.
Copy the data that you want to back up to another disk or disks on Data. Bring Data online, and copy the data by using a backup device that is connected to Data. You can also back up Data over the network to Target. Whether to perform the backup from Data or from Target depends on the following factors:
The availability of a target computer.
Any backup policies that require that backups be performed on designated computers.
The time and cost of performing the backup from data versus transferring the files to target.
IMPORTANTBack up file servers often. If the data is critical, it must be mandatory for users to close their files at the end of the day.
After you have determined the best method for giving Target access to the data it needs to back up, you can begin your backup schedule plan. On Target, run a full, normal backup every Friday. Every Monday through Thursday, run a differential backup to a different tape. Run this program for four weeks before you reuse tapes in the backup program. On every fourth Friday, save the full backup as a permanent archive, which should be stored in a secure, off-site location. Over the course of a year, this method uses at least 31 tapes.
NOTETo allow users access to even more old versions of document files, you can lengthen the backup program to six weeks before tapes are reused. This increases the number of tapes used in a year to at least 41.
If the computer is used seven days a week, add a Saturday and Sunday differential backup to the schedule.
Documenting Backup-and-Restore Procedures
Keeping accurate backup records is essential for locating backed up data quickly, particularly if you have accumulated a large number of backup cartridges. Thorough records include cartridges labels, catalogs, and online log files and log books.
Cartridges labels Labels for write-once cartridges should contain the backup date, the type of backup (normal, incremental, or differential), and a list of contents. If you are restoring from differential or incremental backups, you need to be able to locate the last normal backup and either the last differential backup or all incremental backups that have been created since the last normal backup. Label reusable media, such as tapes or removable disks, sequentially, and keep a log book in which you note the content of cartridges, the backup date, the type of backup, and the date the medium was placed in service. If you have to replace a defective cartridge, label it with the next unused sequential ID, and record it in the log book.
Catalogs Most backup software includes a mechanism for cataloging backup files. Backup stores backup catalogs on the backup cartridge and temporarily loads them into memory. Catalogs are created for each backup set or for each collection of backed up files from one drive.
Log files Log files include the names of all backed up and restored files and directories. A log file is useful when you are restoring data because you can print or read this file from any text editor. Keeping printed logs in a notebook makes it easier to locate specific files. For example, if the tape that contains the catalog of the backup set is corrupted, you can use the printed logs to locate a file.
A verify operation compares the files on disk to the files on the backup cartridge. It occurs after all files are backed up or restored, and it takes about as long as the backup procedure. It is recommended that you perform a verify operation after every backup, especially if you back up to a set of cartridges for long-term storage. A verify operation is also recommended after file recovery.
NOTEIf a verify operation fails for a given file, check the date that the file was last modified. If the file changes between a backup operation and a verify operation, the verify operation fails. Other factors also might cause a verify to fail, such as a change in the size of a file or corruption of the data on the disk or backup cartridge.