My OperaWindows Registry Survival Guide
By Aenn Seidhe PriestS-Priest. Saturday, December 1, 2007 12:43:44 AM
Windows is very susceptible to registry hive corruption. That's anything in \%systemroot%\system32\config . That directory keeps all the registry hives, together with the SAM: SAM - account/password database, SECURITY - security permission/rights database,
default - HKU\Default, software - \HKLM\Software, system - HKLM\System. The same files with an *.alt extension are alternate copies used for the "last known good config" boot option. *.sav is the extension for first-install-run copies of registry hives.
The problem with this is that if the system hive gets corrupted somehow, the whole kaboodle can't boot. And usually when system hive gets corrupted (which is almost certain with, say, BSODs caused by faulty memory sticks), the spare copy also gets corrupted. So "last known good config" may not help much. The "last known good config" option just invokes a copy of the hives made before the last hardware change.
Sometimes the problem is just broken security permissions on registry files after a dirty shutdown. This can be fixed by moving the registry hives to a different partition, then moving them back in.
default - HKU\Default, software - \HKLM\Software, system - HKLM\System. The same files with an *.alt extension are alternate copies used for the "last known good config" boot option. *.sav is the extension for first-install-run copies of registry hives.
The problem with this is that if the system hive gets corrupted somehow, the whole kaboodle can't boot. And usually when system hive gets corrupted (which is almost certain with, say, BSODs caused by faulty memory sticks), the spare copy also gets corrupted. So "last known good config" may not help much. The "last known good config" option just invokes a copy of the hives made before the last hardware change.
Sometimes the problem is just broken security permissions on registry files after a dirty shutdown. This can be fixed by moving the registry hives to a different partition, then moving them back in.
And, some notes on preventive maintenance...
Registry hives should be backed up regularly - manually is fine, as long as there's a spare OS around capable of writing to NTFS (many Linux Live CDs can do that). ntbackup.exe can also archive registry hives.
"Write cache off" is a good option for a system hard drive. Of course it won't help against faulty DIMMs, where data can get corrupted while in RAM and be written back corrupted regardless of a hard drive's cache. But it may help against power cuts.
Which begs for the third - a UPS is a very useful thing.
Also defragmenting the system files, for which System Internals had a utility, helps.
Finally, a simple trick for Windows reinstall without much hassle - an install of Windows from scratch, then all the service pack and such application, drivers install, and - a copy of the old Windows directory over the new one with everything but the newly created registry hives (and SAM, everything in %systemroot%\system32\config) replaced. Then a swap-in of the surviving software hive after the driver setup has been regenerated and the software hive setup matches the system hive.
