![]() ![]() ![]() ![]() ![]() |
Troubleshooting and Configuring the Windows NT/95 Registry
-5-Recovering from an NT Registry FailureThe worst has happened: The Registry has crashed, and you can't get into your computer. Work still has to get done, and deadlines are looming. Don't you wish you could just press Ctrl+Z and make it all come back? Unfortunately, there isn't an Undo for Registry changes, whether they are made manually or generated by the installation of hardware, drivers, or software. But having a good backup and a good plan for restoration is the next best thing. If you wait until the crisis hits to decide what to do, it may make you feel old way too early. If your Registry is gone, it's gone. But this chapter shows you how to get your system going again. Using the Last Known Good ConfigurationMost Registry crashes occur because of something you do: You make a Registry change, you add a driver for hardware, you add software, and so on. The fastest way to recover from a change-induced crash is to return to the last Registry that worked. Every time you boot Windows NT, you are presented with the option of selecting the Last Known Good menu by pressing the spacebar. (See Figure 5.1.) Figure 5.1. The OS 4.0 Loader screen.
Some people have asked whether there is a way to eliminate the Last Known Good menu at startup. Though it may seem like a hassle today, imagine the repercussions of its demise. If you couldn't get to the last saved or last correctly configured Registry, you would have to go to much greater lengths to fix the Registry. Figure 5.2. The Last Known Good menu.
There is an important difference between choosing the default configuration and choosing Last Known Good. If you choose the default configuration, you are returned to the last saved Registry and given options for the hardware profiles. If you choose Last Known Good, you get the Registry that was copied during the last startup for each of the profiles that was used. Your original configuration profile might be from yesterday, but your other Last Known Good profiles might be from some time ago!
Generally, Last Known Good takes care of your problem. You can run your system again, fix the problem, and save the configuration in the \REPAIR directory with RDISK.EXE. Using the Emergency Repair DiskIf Last Known Good doesn't work, the next line of defense is to use the Emergency Repair Disk (ERD) that you created at installation or with RDISK.EXE. It is critical that an ERD is created for every system in the organization, and that it is updated regularly.
Using the ERD is simple, but it requires the three Windows NT installation floppies.
Reboot the system with disk 1 in the floppy drive. It will load many drivers and prompt you for disk 2. Disk 2 reads the hard disk drives for any currently installed instance of Windows NT. If it finds your installation, it prompts you to reinstall, upgrade, or repair the NT version it found.
If you choose to repair the NT version, you must decide which sections of the system to test. Testing options include
You might as well test all of these and fully check your system. Sometimes, the problem is not what you assumed. After you choose to continue, the system detects any mass storage devices (disk drives and controllers), prompts for disk 3, then for the ERD. If you have an ERD, the process is easy. You can restore any or all of the following Registry files, but you might lose configuration data entered since the last update of the ERD. You can restore any of the following Registry files (hives):
After you choose which Registry files you want restored, you'll be prompted to match the files and settings on the ERD with the ones on the hard disk. If files are missing or have different dates or sizes, you'll be notified and prompted to update or skip the files.
If you don't have an ERD, the system must find the files on original media (the location that you installed from). At best, you'll lose all configuration information, meaning you must reconfigure all your devices. It's possible that you'll have to reinstall all your devices. The worst-case scenario is you'll have to reinstall NT from scratch. A Registry restoration through the Repair utility and the ERD will restore most critical settings to your computer. The limitation of the ERD is that it does not cover the full Registry. It does not contain, and therefore cannot restore, all the user settings, file security settings, and shares. Most of the time, though, those are not affected by crashes. Full Registry RestorationA full Registry restoration is dependent on what type of backup you made, what condition the rest of NT is in, and what type of file system you are using. If the system is completely down, the process of getting everything working can be more difficult than if the system is operable but in need of repair. Table 5.1 lists the restoration requirements as they relate to the state of the
system, the file system employed, and the backup type.
Obviously, the best option is to have a full backup available, whether it be a backup (FAT or NTFS) or a copy (FAT only). Any other option means a lot of work, and potentially reinstall- ing NT.
Whatever method you choose to protect your Registry, protect it so you don't have to reconstruct your system from scratch.
Restoring Your System with NT BackupIn the previous chapter, you saw how to back up the system using NT Backup. Restoring the system is also very easy. The only caveat is that NT must be installed, the system files must be in the same directory as the original (such as C:\WINNT), and a supported tape drive must be running. After launching NT Backup with Start | Programs | Administrative Tools | Backup,
select the Tapes window (as shown in Figure 5.3). Select the tape and tape set you
would like to use. If you want to restore only part of the current tape set (only some of the directories or files), double-click the tape-set name. NT Backup performs a Catalog Status procedure to list all the files that are contained on the tape. This procedure is very similar to a DIR command in DOS, except that it takes longer. Select and deselect files as necessary (as Figure 5.4 illustrates). After you choose the files and directories, confirm the options for the restoration with Operations | Restore. If you want the Registry to be restored to the local system, you must select it in the dialog box shown in Figure 5.5. Selecting the files in the catalog is not enough. If you do not select Restore Local Registry from the Restore Information dialog box, you will receive a File in Use error, and the files will not be restored. Figure 5.4. Choose which directories and files will be restored. Figure 5.5. The Restore Information dialog box.
Figure 5.6. The choice to overwrite is yours.
SummaryYour ability to recover from a disastrous system crash is fully dependent on the quality of your backup. Without a conscientious effort to protect your information, you will spend too many hours trying to recover, only to find that full recovery is impossible. After you have created good backups, protect them well. With that backup information, you can then quickly recover, regardless of the level of problem. If the problem is minor, use Last Known Good. If it is a little more serious, you can probably recover with your Emergency Repair Disk. If neither of those will restore the required information, use the backups created with your backup software. |
||||||||||||||||||||||||||||||||||||||||||||||||
|