Windows 98 Professional Reference

- 20 -
Backup and Restore

• Evaluating Backup Requirements
  • Choosing Backup Hardware
  • Choosing Backup Software
  • Choosing a Backup Rotation Strategy
• Using Microsoft Backup
• Conclusion

If you're a systems professional, then you should already know about the importance of good backups of the system and of important data. If you don't know this, then it's probably the most important lesson you can take away from this book: Making regular backups is a requirement when using computers. Period.

Horror stories abound to teach this lesson, and you usually don't have to work with computers (particularly PCs) for very long before you get your own lesson in backups. There's nothing quite like getting a call from someone asking for help and discovering that their data is beyond repair, and then hearing that long silence on the telephone after you ask the question, "When did you make your last backup?" People sometimes lose months of work because of failures to perform regular backups

using a good procedure, and sometimes they lose months of other people's work, too. The amount of dollars lost in such incidents can be staggering.

There are many reasons that backups fail, including the following:

• Reliance on users to make their own backups in some fashion. This is a recipe for disaster because in any group of users, the ones who will actually do this regularly probably don't exceed 5% of the total.
• Failure to periodically attempt restoration from backups. Situations can arise in which the backup software and hardware seem to be working fine, but in actuality don't contain data that can be restored.
• Failure to log or track backups, or to set up a system so that more than one person keeps an eye on things to ensure that the backups are being properly performed.

• Failure to use adequate tape rotation schemes. Tapes can and do go bad, and they'll inevitably go bad just when you actually need to restore from them, so it's important to have sufficient backup media so that a good rotation scheme can be put into place.

Windows 98 will not often be used to store files for many users, and so the subject of backups is necessarily more limited than it would be for, say, a network file server. However, there are situations in which data must be backed up from a Windows 98 system, and a solid grasp of the different techniques and software you can use with Windows 98 backups is an important topic.

Evaluating Backup Requirements

When evaluating specific backup requirements in a given situation, start by looking at the value of the information--or the cost to replace it--should it be lost. This should be known for different periods of time, as well. For instance, it may be a trivial matter to lose a single day's worth of data because very little data might be accumulated in a day and it might be easily re-entered. But it may be far more than ten times as expensive to lose ten days worth of data, because the source data may be more difficult to retrieve after a period of time, or the productivity impact from rebuilding that data may not be as easily borne. You should think about impacts resulting from losing a day's data, a week's data, a month's data, and three month's data. If it's not a linear curve, then you have to take that into account when you design the backup strategy.

Next, you need to know the amount of data that must be backed up, both infrequently and frequently. For instance, on a system that runs a simple, stable set of applications, it's probably required that you do a complete backup of the entire system (operating system, applications, and data) only every week or every month, whereas you may need to back up the actual data files on a daily basis. You'll need to know the amount of data required for both types of backups in this situation.

As part of calculating the backup size requirements, keep in mind that certain aspects of the system probably don't require backing up if you have the source media. Even in the case of a catastrophic hardware failure, you should have your original operating system and application installation media that you can use to quickly rebuild the system, and your backups may only need to store the actual data files. (However, even when this is the case, it's always a good idea to get a complete system backup at least once in a while as an added measure of security.)

---

TIP: For critical systems, it's a good idea to maintain a "rebuild kit" that contains all the information you would need to rebuild the system from scratch. This kit should be readily available and should be designed to speed the rebuilding of the system (because you invariably need it at 2:00 a.m. because the system is required when people come to work in a few hours). Rebuild kits should contain, at a minimum, an Emergency Boot Disk (EBD) for the system, all of the operating system and application CD-ROMs or disks, the hardware diagnostic and setup programs, and whatever instructions would be necessary to set the system up again should the hard disk or another key component need to be replaced. Additionally, you can keep information in the rebuild kit on service providers, the exact configuration of the system when it was built, the original invoice for any warranty disputes that may arise, and a log book in which all changes to the system are written.

---

The next thing to evaluate is how much time you have to perform the backup. Some systems may need to be available nearly 24 hours a day, so this can be an important thing to know. Most systems, however, can easily be taken down and made available for backups at night or over weekends. Often, backups can be started as the last person leaves, and let run overnight. Still, make sure you evaluate this.

Finally, evaluate whether there are existing backup systems in place on which you can "piggyback." For example, an individual system may be able to simply copy its data files up to a network file server every night, where it is then backed up by the same large-scale backup system that takes care of the file server itself. Alternately, if an organization is already using a large number of DAT backup devices, then it would be a good idea to stick with that standard unless there is a compelling reason to use a different type of system. Yet another alternative is to install special client software that works with a network backup system to back up individual workstations over a network.

All of the above factors (plus, of course, your budget) should help you to choose appropriate backup hardware, software, and a plan.

Choosing Backup Hardware

Assuming that you must purchase new backup hardware for a system, you will find a number of proven, good choices, depending on your actual needs. When choosing a backup technology, consider the following factors:

• Reliability of the hardware and the media
• Cost of the hardware and the media
• Storage capacity
• Likely frequency of restorations

• Importance of fitting entire backup onto a single piece of media

Table 20.1 reviews different types of backup technologies, their approximate costs, and the relative pros and cons of each. that prices of drives, media, and costs per MB in Table 20.1 are approximate.

Table 20.1 Backup Technologies

Choosing Backup Software

Windows 98 includes a vastly improved backup and restore application called Microsoft Backup (discussed in detail in the later section "Using Microsoft Backup"). Microsoft Backup was developed for Windows 98 by Seagate Software, makers of a more comprehensive backup product called Backup Exec. Obviously, because Microsoft Backup is included for free with Windows 98, you should consider it as a first alternative.

Microsoft Backup may not meet your needs, however. The main limitation is that it is not possible to set up scheduled backups with it that start at a specified time. You must start the backups manually. However, you can pre-select files or directories and load the backup settings from a file, easing this burden somewhat.

If Microsoft Backup doesn't meet your needs, there are many other alternatives, most of them reasonably priced. The first option is to upgrade to Backup Exec from Seagate Software. There are also many other third-party backup software solutions from numerous vendors, such as Norton Backup from Symantec. Most of these programs cost less than $100 and will work with virtually all tape drives. Also, the tape drive that you purchase may come with backup software included for Windows 95 or Windows 98.

Choosing a Backup Rotation Strategy

With all of the preceding information known, you can now plan a backup rotation strategy, which addresses how backup media is rotated. Backup rotations are designed to accomplish the following goals:

• Rebuild the system, with the most recent possible data, in case of a catastrophic failure.
• Restore files from older tapes that may have been accidentally erased or damaged and not quickly noticed.
• Protect against backup media failure.

• Protect the data from an environmental failure, such as a fire, that would destroy the original system and data.

Windows 98 maintains a special bit for each file on the system called the archive bit. The archive bit indicates the backup status of the file. When a file is modified, its archive bit is set to "on," indicating that the file should be backed up. When the backup is accomplished, the archive bit is cleared. By using this archive bit and the backup software (Microsoft Backup or others all work the same way in this regard), you can make the following types of backups:

• A full backup, where all selected directories and files are backed up, regardless of their archive bit state. Full backups clear the archive bit on all of the backed-up files when the backup is finished.
• An incremental backup, where only files with their archive bit set are backed up. This backs up all files changed since the last full or incremental backup. Incremental backups clear the archive bit of the backed-up files; those files will not be backed up during the next incremental backup unless they are modified again and their archive bits set back on.

• A differential backup, which is similar to the incremental backup in that it backs up only files with their archive bits set. The key difference in a differential backup is that the archive bits are left on. Subsequent differential backups will back up those same files again, plus any new ones that have been modified

In a perfect world, it would be nice to always perform full backups. If the system were to fail, you would need only the most recent backup tape to fully restore the system. However, there are a number of reasons why it may not be desirable to do a full backup all the time. For one thing, perhaps there is inadequate time to perform a full backup each day. Another reason is to extend the life of your media and tape drive by reducing the amount of work that they must do. This needs to be balanced against the increased time it takes to restore from a combination of full and incremental or differential backups, however, and the increased possibility of being unable to properly restore from a combination approach.

One common way that these types of backups are mixed is to perform a full backup of the system once a week, and only perform incremental or differential backups each day of the week. Examine the following examples:

• Perform a full backup every Friday night, and incremental backups on Monday through Thursday. If the system fails Monday morning before any data is entered, you only need to restore the full backup from the previous Friday night. If, however, the system fails on, say, Thursday morning, you have to sequentially restore four tapes in order to retrieve all of the data: the full backup from the previous Friday, then the incremental tapes from Monday, Tuesday, and Wednesday nights. Moreover, in order to guarantee the integrity of the data, you must be able to restore all of those tapes, and in their proper sequence. Otherwise, you run the risk of ending up with mismatched data files. In this scenario, you have four media-based points of failure, which might be more risk than you care for.

• Perform a full backup every Friday night, and differential backups Monday through Thursday. In this scenario, if the system fails Monday morning, you just restore the previous Friday night's tape. However, if the system fails on Thursday morning, you only have to restore two tapes: The last full backup from Friday night, plus the differential backup from Wednesday night. Because differential backups continually back up all changed files since the last full backup, you never need to restore more than two tapes, thereby reducing the number of possible points of media failure

The general rule of thumb is this: Incremental backups generally minimize the amount of time needed to perform each daily backup, but they take longer to restore and you have a greater risk of media failure. Differential backups take longer to make, but reduce the time required to restore and reduce the risk of media failure.

All of this needs to be balanced against the nature of the data, the amount of risk you're willing to take versus the cost of each back up, the capacity of the tapes, and the amount of time in which you must make each regular backup.

The most common backup rotation scheme is called Grandfather-Father-Son (GFS). A common way to implement this scheme is to use at least eight tapes. Four of the tapes are labeled "Monday" through "Thursday." Four more tapes are labeled "Friday 1," "Friday 2," up to "Friday 4." Each day Monday through Thursday you use one of those labeled tapes, replacing the data stored the previous week. Each Friday tape corresponds to which Friday in the month you are on: On the first Friday you use Friday 1, and so forth. Finally, on the last day of each month you prepare a month-end tape, which is not reused, but is instead kept off-site in case an environmental failure destroys the system and all locally stored tapes.

There are three main variations of the GFS scheme. In the first, you simply make a full backup of the system, each and every time you perform a backup. This offers the greatest amount of media redundancy and the minimum amount of restoration time. In the second, you perform a full backup on each of the Friday tapes and the monthly tape, but only perform incremental backups during the week. In the third, you do much the same thing, but use differential backups instead of incremental backups.

---

TIP: If your data is super-critical and not easily reconstructed, you can often perform full backups every night, and also squeeze in a quick incremental backup at lunch time. This way you can't lose more than a half-day's worth of data instead of a full day.

---

You can also choose simpler rotation schemes instead of GFS. For instance, you may just use two or three tapes, and rotate them in sequence, overwriting the old data each time you do so. This lets you restore to any of the previous three day's data. The shortfall here is that sometimes you may need to go back further in time to restore data that had been erased or damaged without anyone immediately noticing it. You can combat this problem by using several week-end or month-end rotating tapes.

---

Why Would You Want to Limit the Number of Tapes You Keep?

---

In these litigious times, it can be advisable to limit the number of backup tapes you keep. If your company were sued, it's possible that all computer files relating to a particular matter could be required to be produced to satisfy a subpoena. If this happens, and you have hundreds of backup tapes going back several years, your company may well have to carefully examine all of the files on each and every backup tape in order to locate all of the required information. You can imagine the nightmare that would ensue! (And you can also bet that the brunt of it would fall onto your shoulders!) You should consult with your company's legal counsel about the advisability of putting into place an "electronic document retention policy" where you make a tradeoff between this risk and the risk of data loss and arrive at some happy compromise. For instance, perhaps you might set up a scheme where you implement GFS as described previously, but destroy all tapes older than one year (or reuse them--it doesn't really matter which). This would limit the number of backups that would need to be searched to 20 tapes (12 monthly tapes, four weekly tapes, and four daily tapes).

---

One factor to keep in mind when considering different tape rotation schemes is the granularity of your backups. Broadly speaking, this is the flexibility you retain to recover data from earlier tapes. In the standard GFS scheme in which full backups are made all the time, you can restore a file from any given day for a week's time, for any given week-ending (Friday) for a month's time, or for any given month for a year's time. You could not, however, restore a file that was created three months ago in the middle of the month and erased (or damaged) before the month was over, because a clean copy wouldn't exist on any of the backup tapes.

---

Granularity and Data Corruption: A Tricky Balance

---

One reason to carefully consider granularity is the possibility of data becoming corrupt and the situation not being noticed. For instance, this author once worked with a database file that had been corrupted several weeks earlier, but had been continuing to function and seemed normal. As problems developed, however, and we worked to solve the problem, the database vendor's technical support staff discovered that a portion of the database that wasn't regularly used had become lost and wasn't repairable. The only way to recover the database and ensure that it was clean was to restore backups, further and further back in time, until a copy of the database that didn't have the damage was restored, and then re-enter the data that was added since that time. Because of the increasing granularity of backups as we had to go further and further back into time, the amount of data that would need to be re-entered grew almost exponentially.

---

The best advice you can take for choosing a rotation scheme for important data is this: Unless there are reasons to do otherwise (as already discussed), use the GFS scheme with full backups every time, and destroy tapes older than one year. This maximizes the safety of your data, maximizes your restoration flexibility, minimizes the risk of media failure, and keeps any legal risk to a reasonable minimum. If other factors force you to choose a different scheme, use the discussions in this section to arrive at the best compromise for a given situation.

---

TIP: After arriving at a proposed backup scheme, it's important to discuss the relative merits and capabilities with interested parties in your company's management structure. At a minimum, this will probably include the Controller, CFO, COO, and possible the CEO. There may be other members of upper management, too, who should understand the restoration capabilities you will have going forward. The last thing you want to have happen in case of data loss is having a bunch of people pointing fingers in your direction for having an "inadequate" backup scheme in place.

---

Using Microsoft Backup

As previously discussed, Windows 98 includes new backup software--an improvement over the backup software included with Windows 95. Called Microsoft Backup, the software is made by Seagate Software, makers of the popular product Backup Exec. Microsoft Backup sports the following features:

• Works with virtually all tape and removable media devices based on ATAPI/IDE and SCSI interfaces
• Can back up to other hard disks, floppy disks, and network shares
• Allows selection of specific files and directories, or entire hard disk partitions; also lets you ignore files based on file specifications
• Supports full, incremental, and differential backups
• Backs up Windows 98 long filenames
• Backs up the Windows Registry

• Can compress and verify backup data

The only real limitation to Microsoft Backup is that it does not support unattended scheduled backups. Instead, backups must be initiated manually.

---

NOTE: Microsoft Backup is not installed as part of a typical Windows 98 installation. Use the Add/Remove Programs Control Panel to add it to a Windows 98 system.

---

You start Microsoft Backup by opening the Start menu, Programs, Accessories, System Tools menu. When it begins, you see the screen shown in Figure 20.1.

Figure 20.1

Starting Microsoft Backup.

From the opening screen, you can choose to create a new backup, open a previously saved backup, or restore files. Each of these choices starts a wizard that walks you through the requisite steps. Or, to access the entire Microsoft Backup program, you can click the Close button, which brings up the full program from which you can perform any of these functions, shown in Figure 20.2.

Figure 20.2

Microsoft Backup's main window with the Backup tab selected.

Select either the Backup or Restore tab to perform that respective function. Using the Backup tab, use the left pane to open and select drives and directories. Selected directories display their file contents in the right pane, where you can select individual files. Clicking on a checkbox selects or deselects a directory or file for backup.

You can choose from a variety of backup options with the Options button, which displays the Backup Job Options dialog box shown in Figure 20.3.

Using the Backup Job Options dialog box, you can choose from the following options:

• On the General tab, you can choose whether to perform a comparison of the backed-up data to the original to confirm that the tape contains valid data. You can also choose whether to compress the data on the backup device, which may increase the amount of data that can be stored, depending on the level of compression in the original files (you should not choose to compress data that is already compressed because this actually increases the amount of space needed in the backup). Finally, you can choose whether backups overwrite earlier data.
• The Password tab lets you establish a password for the backup. The data cannot be restored if the password is not known.
• The Type tab lets you choose between full, incremental, and differential backup types.
• The Exclude tab lets you skip files based on file specifications you can enter.
• The Report tab lets you choose what information is shown in the post-backup report.
• The Advanced tab lets you choose whether to include a copy of the Windows Registry in the backup.

Figure 20.3

Backup Job Options dialog box.

After selecting a set of files and choosing your backup job options, you can estimate the amount of space required for the backup. Pull down the View menu and choose Selection Information to see the estimate.

Before running a backup, you should save the backup criteria if you expect to perform similar backups in the future. Use the Save As command in the File menu to do this.

The Restore tab lets you choose restoration options. Microsoft Backup keeps a catalog of backups you've made. You use these catalogs to restore files or complete backup sets. Figure 20.4 shows the Restore tab.

To restore files, select them using the selection panes just as you do for selecting files to back up. Also, check the Restore Options dialog box by clicking the Options button, shown in Figure 20.5.

The Restore Options dialog box is simpler than the Backup Options dialog box, and lets you choose from the following options:

• The General tab lets you choose how files should be restored when the file exists in the restore destination.
• The Report tab lets you choose what information is reported after the restoration is complete.

• The Advanced tab lets you choose whether to restore the Windows Registry.

Figure 20.4

Microsoft Backup's Restore tab.

Figure 20.5

Restore Options dialog box.

As you can see, using Microsoft Backup is straightforward. It is a well-designed, reliable backup and restoration program that should meet most common backup software needs.

Conclusion

Performing regular system backups is an important responsibility. The reliability of today's computer hardware (particularly hard disks) often makes this seem like a thankless and useless chore, but having a good backup available will eventually save you many headaches, and possibly save your job if they're your responsibility. In this chapter, you learned about general backup technology, different backup hardware and media choices, different backup software choices, and how to design a good backup program given different needs. You also learned about Microsoft Backup, a good general-purpose backup program that is included with Windows 98.

� Copyright, Macmillan Computer Publishing. All rights reserved.