by Tim Parker

IN THIS CHAPTER

• What Is Lone-Tar?

• Using Lone-Tar's Interface

• Installing Lone-Tar

• Backing Up with Lone-Tar

• Verifying Files

• Restoring Files

• Utilities and Environment: Tweaking Lone-Tar

As you saw in Chapter 38, "System Administration Basics," making backups on your Linux system can be a complex and often annoying procedure, especially if you don't have a high-capacity tape drive or other backup storage device. If you have to rely on floppies for a backup, you are really in for a frustrating time, because a full backup can take dozens (if not hundreds) of disks. When floppies are all that's available, most users don't even bother.

Many users find the normal backup utility tar difficult and unfriendly to work with. On top of that, tar can error out for any number of conditions, causing you to have to restart your backup from the beginning. In many larger UNIX environments, the use of tar has been replaced by custom-designed GUI-driven backup utilities, but Linux hasn't quite caught up to that point yet. There are, however, a few alternatives to using straightforward tar, and the best of these is Lone Star Software's Lone-Tar. An evaluation copy of Lone-Tar has been graciously provided by Lone Star Software on the CD-ROM accompanying this book. It's definitely worth trying out!

Lone-Tar can best be thought of as a super version of tar. It provides all the features of tar yet adds some functionality that tar lacks. To be very safe, Lone-Tar does not use the standard tar utility, although its behavior is similar. Lone-Tar is available for many UNIX and non-UNIX platforms and is compatible across them all. You could, for example, use a DOS version of Lone-Tar to back up files to a tape, and then read them into your Linux system.

Like tar, Lone-Tar can back up and restore entire file systems to and from disks, tape, auxiliary hard disks, and other storage media. Lone-Tar goes beyond normal tar in that all special files, links (symbolic and otherwise), virtual files, and partitions can be handled as easily as standard files.

Lone-Tar can also allow backups and restores of dual drives with different capacities, which tar is not easily capable of doing. Most important, Lone-Tar has an excellent error-recovery procedure built in that allows recovery of a file system or files on a backup medium, even when that medium has developed errors. When tar encounters problems with a backup medium, it terminates, effectively ruining the value of that backup set.

Lone-Tar has two interfaces: menu-driven and command line. The command-line interface is very similar to the tar command's syntax for compatibility's sake. This way, someone who has been using tar for many years and moves to Lone-Tar for the extra capabilities it offers doesn't have to relearn a whole new command set. As you might have discovered by now, tar's command set is rather uninspiring, awkward, and difficult to master.

It does take years of use to feel comfortable with tar's command line, so for that reason Lone Star Software designed a friendlier menu-driven interface too. You can use either the command line or the menu-driven interface to perform all of Lone-Tar's functions, and they work the same. The menu-driven interface is much easier to work with, though, especially if you haven't mastered tar.

You can see the difference between the two interface methods by a quick look at the syntax of Lone-Tar. The syntax, very similar to tar's syntax, looks like this:

lone-tar [MIcCrtTUxPZ] [bdefhklmnpvFEADVR] [tapefile] [block size]

 [compression limit] [0-9] [floppy/tape size] files ...

If you are not exactly right with one of the command-line parameters, both tar and Lone-Tar give you pages of error codes and options. You can display the command-line help screen, shown in Figure 67.1, at any time by simply typing

lone-tar

at the command line.

The menu-driven interface, on the other hand, shown in Figure 67.2, is much more friendly and easier to figure out. Each of the primary menu options leads to another menu, with mnemonic startup commands for each choice.

The choice of interface you use is up to you, of course, but if you are not familiar with tar's awkward syntax, you should stick to the menu-driven interface. UNIX veterans might want to stay with the command-line interface, but the menu-driven system is much easier to work with and eliminates the chance of typing errors. For most of this chapter, we'll work with the menu-driven interface.

The installation process for Lone-Tar is pretty simple. You need to log in as root, and then change to the /tmp directory. You then should extract all the files from the CD-ROM or disk (if you have put the Lone-Tar software on the disk) with a tar command. For example, if you have copied the Lone-Tar files to a floppy in drive A, you would log into the system as root and issue the following two commands:

cd /tmp

tar xvf /dev/rfd0

The tar command tells Linux to extract all the files from the first floppy drive (/dev/rfd0) and store them in the current directory.

If you are installing from CD-ROM, you can copy the files to the /tmp directory directly using cp. For example, if the files are stored on the CD-ROM in the directory /lone-tar and the CD-ROM is mounted to your Linux system in the directory /cdrom, you would issue these commands:

cd /tmp

cp /cdrom/lone-tar/* 

The exact command line you use depends on the location of the Lone-Tar files on the CD-ROM and the mount location on your system.

After the files are all safely in the /tmp directory, you can start the installation process by issuing this command:

./init.ltar

This program was written by Lone Star Software to install all the components of Lone-Tar properly. You are asked a bunch of questions about your tape or backup drive, its capacity, and whether you want to print the online manuals. If you don't want to print the manuals during the installation process, you can print them at any time from the Lone-Tar menu.

To start the Lone-Tar system in menu-driven mode, issue the following command:

ltmenu

You should then see a screen like the one shown in Figure 67.3. Pressing Enter takes you to the main menu, shown previously in Figure 67.2. If you want to use your Lone-Tar system in command mode, use the command

lone-tar

Backups are a vital part of any Linux system, whether you use your system for serious work or just for playing. The reason is simple: Reloading your Linux system, reconfiguring it the way it was, and reloading all your applications can take a long time and can sometimes lead to errors. Recovering from a backup tape or other backup device can take a few minutes and requires little intervention on your part. If you have important information stored on your Linux system, you really should have regular backups made for safety's sake, because it's often impossible to reconstruct data you lost.

Lone-Tar lets you make two kinds of backups: Masters and Incrementals. The Master backup is a complete backup of your system, with every file on the file systems backed up safely. An Incremental backup is made between Masters and holds the changes to the system since the last Master. Incremental mode lets you make backups much quicker, because there is no need to back up every file. Linux knows which files have changed because of the attributes attached to each file, and the files that have been created or modified since the last Master backup are written to the backup medium. In case of a problem and a reload, the Master is reloaded first, and then the Incrementals made since the Master. If you've lost a file or two, you can often get them from the Incremental itself.

The manner in which you create Master and Incremental backups will depend on how much you use your system, how much data you change daily, and how important your system is to you. For example, a regularly used system could get a Master backup once a week to a high-capacity drive. Incrementals could be performed automatically each night.

If you don't use your system much, you can do Master backups once a month and Incrementals weekly, although this isn't really recommended. For heavily loaded systems, you might want to forget about Incrementals altogether and make a new Master backup every night. One of Lone-Tar's strengths is the capability to automate backups, as you will see.

To make an Incremental backup, you follow the same process. Because most Incremental backups are much smaller than a Master backup, they also back up much faster. You really should get in the habit of making Incremental backups either every day you use the Linux system or whenever you save something you really can't afford to lose. It's better to spend 10 minutes making a backup than four hours re-creating that chapter of your latest book!

A selective backup, started using the S option on the Lone-Tar menu, lets you back up only specific areas of your system. You are asked which files or directories to include or exclude, and then the backup proceeds normally.

The Verify option provided by Lone-Tar is a security precaution that you should use every time you make a backup. The Verify option scans the backup and compares it to the original files. This action ensures that any backup errors are caught before they become serious. It is a good habit to verify each backup after it has been made. This is especially true when you have made new Master backups.

Remember that some files on your system might change between the backup time and the verification time, depending on whether the system was used between the two times. Some automated procedures, such as mail, logging, news, and automated background tasks, alter files while a backup or verification is proceeding. Lone-Tar finds the files different and reports errors to you. You should carefully read the reports from the verification process so that you know which errors are important and which are due to these system changes.

When you have to restore a file, a directory, or an entire file system, find the proper backups. If you have been using the Master and Incremental routine, you need the last Master and all the Incrementals since that Master was made. Alternatively, if you are just looking for a few files you accidentally deleted, you might know which tape or drive they are on and can use just that medium.

To start a restore process, select the R option from the Lone-Tar main menu. This brings up the Restore menu, shown in Figure 67.7. Most of the options on the Restore menu are self-explanatory. For example, to restore an entire tape, you would use the option Restore entire tape to hard disk.

If more than one tape or other device is involved in the backup, Lone-Tar prompts you to insert the next volume. It keeps doing so until the restore process is complete.

If you are restoring from a combination of Masters and Incrementals, you must repeat the restore process for each tape. For example, if you accidentally erased an entire directory, you could use the last Master backup to get the main files, and then go through all the Incrementals made since the Master was created to obtain any changes. You have to perform the updates manually using the Restore menu.

After the restoration is completed, Lone-Tar returns to the main menu. You should verify that the backup was to the proper location and that everything looks correct.

Tape-Tell is a special feature of Lone-Tar that tells you a little about when the tape was used. This information hinges on the Lone-Tar file that can be put at the beginning of the medium. We discussed this file earlier, in the section "Backing Up with Lone-Tar."

The Lone-Tar Utilities menu, shown in Figure 67.8, holds several useful commands and functions. Most of these options are self-explanatory, and a few are very handy for users. It is helpful to check the backup date of the last Master backup occasionally as a reminder of when you should start thinking about a new Master backup.

The automated use of Lone-Tar through cron is a neat feature that lets your system make backups without your being there. As you know from earlier chapters in this book, cron lets you schedule commands to be run at particular times or intervals, so you can easily set Lone-Tar to be run by cron to create Incremental backups every night, twice a week, or whenever you want. You don't need to know details about cron to schedule backups--Lone-Tar takes care of that for you.