Preventative Computer Maintenance

The best way to deal with problems is to stop them from happening in the first place. That's where preventative maintenance comes in.

A good preventative maintenance program incorporates a comprehensive backup plan, measures to secure the system against malicious exploits, periodic hardware and software maintenance, and steps to maintain general system tidiness. The goals of preventative maintenance are to reduce the likelihood of hardware failures, extend the useful life of the system, minimize system crashes caused by outdated drivers and other software problems, secure the system against viruses and other malware, and prevent data loss. The following sections outline a basic preventative maintenance program that you can use as a basis for developing a program that fits your own and your system's needs.

Backing up the system
Maintaining a good set of backups is a critical part of preventative maintenance. The availability of inexpensive hard drives and motherboards that support RAID 1 mirroring had led many people to depend solely on RAID 1 to protect their data. That's a very bad idea. RAID 1 protects only against the failure of a hard drive, which is partial protection at best. RAID 1 does nothing to protect against:

• Data being corrupted by viruses or hardware problems
• Accidentally deleting, overwriting, or modifying important files
• Catastrophic data loss, such as fire or theft of your equipment

To protect against those and other threats, the only reliable solution is to make backup copies of your data periodically to some form of removable media, such as tapes, optical discs, or removable hard drives.

Backup hardware
In the past, there weren't any really good hardware choices for backing up home and SOHO systems. Tape drives were expensive, complex to install and configure, used fragile and expensive media, and were painfully slow. CD writers, although reasonably fast and inexpensive, stored such a small amount of data that many people who used them for backing up were reminded of the Bad Olde Days of swapping floppy disks. External hard drives were expensive and of dubious reliability.

Things have changed. Consumer-grade tape drives are still expensive and slow, although it's easier to install a modern ATAPI tape drive than it was in the days when tape drives used SCSI or proprietary interfaces. CD writers are still reasonably fast and inexpensive, and are a good solution if your data fits on one or two CDs.

Organizing your data directory structure
If you back up to hard drives, you can back up your entire drive every time. If you use a DVD writer, you'll probably do full backups infrequently, with routine backups only of your data files. In that case, it's important to organize your data directories to make it as easy as possible to back up only your data while making sure that you back up all of your data. The trick here is to segregate your data into groups that can be backed up with different frequencies.

For example, our data, excluding audio and video files, totals about 30 GB. Obviously, it's impractical to back that much data up to DVDs routinely. Fortunately, it's not necessary to back it all up every time. Much of that data is historical stuff books we wrote years ago (and that we may update sometime), old email, and so on. That all needs to be backed up, but it's not necessary to back it up every day or even every month. So we segregate our data into subdirectories of three top-level directories:

data

This top-level directory contains our current working data email, current book projects, recent digital camera images, and so on. This directory is backed up every day to DVD, and frequently throughout the day to mirror directories on other systems on our network. We never allow this directory to grow larger than will fit on one DVD.

archive
This top-level directory contains all of our old data: files that we may not need from one month to the next, or even from one year to the next. This directory is backed up to multiple redundant sets of DVDs, two of which are stored off-site. Each backup set currently requires six DVDs. Every time we add data to the archive directories, which doesn't happen often, we burn several new sets of backup DVDs. (We keep the old discs, too, but then we're packrats.)

holding
This top-level directory is intermediate between our working data directories and our archive directories. When the size of our working data directories approaches what will fit on one DVD, usually every two or three months, we sweep older files to the holding directory and burn new copies of the holding directory to DVD. By doing this, we can keep our working data directory at a manageable size, but not have to redo the archive directory backups very often. We also keep the size of this directory to what will fit on one DVD. When it approaches that size, we sweep everything in the holding directory to the archive directory and burn a new set of archive DVDs.

When you plan your data directory structure, it's also important to consider these aspects:

• The importance of the data
• How difficult it would be to reconstruct the data
• How often the data changes

In combination, these three factors determine how often data needs to be backed up, how many generations of backup copies you'll want to retain, and therefore where the data belongs in your directory structure. For example, your financial records and digital photographs are probably critically important to you, difficult or impossible to reconstruct if lost, and change frequently. Those files need to be backed up frequently, and you'll probably want to maintain several generations of backup copies. Those files belong in your working data directories.

Conversely, if you've ripped your CD collection to MP3s, those files are neither important nor difficult to reconstruct because you can simply re-rip the CDs if necessary. Although these files might reasonably be classified as data, chances are you'll categorize them as data that never needs to be backed up and therefore locate them somewhere in your directory structure outside the directories that are routinely backed up.

Developing a backup rotation scheme
Whatever backup hardware you use, it's important to develop an appropriate backup rotation scheme. A good rotation scheme requires half a dozen or more discs, tapes, or drives, and allows you to:

• Recover a recent copy of any file easily and quickly
• Recover multiple generations of a file
• Maintain multiple copies of your data for redundancy and historical granularity
• Store at least one copy of your data off-site to protect against catastrophic data loss

The most popular backup rotation scheme, and the one most suitable for backups to DVD+RW discs, is called Grandfather-Father-Son (GFS). To use this backup rotation, label the following discs: Five (or six) daily discs, labeled Monday through Friday (or Saturday).
Five weekly discs, labeled Week 1 through Week 5.
Twelve monthly discs, labeled January through December.
Back up each working day to the appropriate daily disc. On Sunday, back up to whichever numbered weekly disc corresponds to the number of that Sunday in the month. The first (or last) of each month, back up to the monthly disc. This method gives you daily granularity for the preceding week, weekly granularity for the preceding month, and monthly granularity for the preceding year. For most home and SOHO users, that scheme is more than sufficient.

You can, of course, modify the standard GFS rotation in whatever way is suitable to your needs. For example, rather than writing your weekly or monthly backups to a DVD+RW disc that will eventually be overwritten, you can write those backups to DVD+R (write-once) discs and archive them. Similarly, there's nothing to prevent you from making a second backup disc every week or every month and archiving it off-site.

If you're backing up to external or removable hard drives, you probably won't want to use the standard GFS rotation, which would require 22 hard drives. Fortunately, you can use fewer drives without significantly compromising the reliability of your backup system. Most removable hard drives have room for at least two or three full backups, if you back up your entire hard drive, or a dozen or more data-only backups.

You still don't want to keep all your eggs in one basket, but it's reasonable to limit the number of baskets to as few as two or three. The trick is to make sure that you alternate the use of the drives so that you don't end up with all of your recent backups on one drive and only older backups on another. For example, if you decide to use only two external or removable hard drives for backup, label one of them M-W-F and the other Tu-Th-S, and alternate your daily backups between the two drives. Similarly, label one of the drives 1-3-5 and the other 2-4 for your weekly backups, and one drive J-M-M-J-S-N and the other F-A-J-A-O-D for your monthly backups.

Choosing backup software
There are four broad categories of software that can be used for backing up. Each has advantages and drawbacks, and which is best for you depends on your needs and preferences.

System utilities
System utilities such as xcopy are free, flexible, easy to use, can be scripted, and create backups that are directly readable without a restore operation. They do not, however, typically provide compression or any easy means of doing a binary compare on each file that has been copied, and they can write only to a mounted device that's visible to the operating system as a drive. (In other words, you can't use them to write to an optical disc unless you're running packet-writing software that causes that disc to appear to the operating system as a drive.)

Traditional backup applications
Traditional backup applications such as BackUp MyPC (http://www.stompsoft.com) do only one thing, but they do it very well. They are fast, flexible, have robust compression and verification options, support nearly any type of backup media, and allow you to define standard backup procedures using scripting, detailed file selection criteria, and saved backup sets. If your needs are simple, the bundled Windows backup applet, which is a stripped-down version of Veritas Backup Exec (since sold and renamed BackUp MyPC) may suffice. Otherwise, we think the commercial BackUp MyPC is the best option for Windows users.

Disk imaging applications
Disk imaging applications, such as Acronis True Image (http://www.acronis.com) produce a compressed image of your hard drive, which can be written to a hard drive, optical disc, or tape. Although they are less flexible than a traditional backup application, disk imaging applications have the inestimable advantage of providing disaster recovery features. For example, if your hard drive fails and you have a current disk image, you needn't reinstall Windows and all your applications (including the backup application) and then restore your data. Instead, you simply boot the disaster recovery disc and let 'er rip. Your system will be back to its original state in minutes rather than hours.

We use three of these four software types on our own network. Several times a day, we do what we call "xcopy backups" even though we now run Linux instead of Windows to make quick copies of our current working data to other systems on the network. We use a CD/DVD burning application, K3b for Linux in our case, to run our routine backups to DVDs. And, when we're about to tear a system down to repair or upgrade it, we run an image backup with Acronis True Image, just in case the worst happens.

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