If the backups are questionable then you can DCpromo the servers down and
back up and this will recreate the ntds.dit and replicate the info from a
good dc as long as one exists. .
There are three fundamental ways that data on disk becomes corrupted:
- The wrong data is written to the storage media.
- The data is damaged or changed after being stored.
- Data is written to the wrong place on the storage media.
RESOLUTION
==========
A page that reports a -1018 error cannot be repaired; one way or another it
must be expunged from the database. There are three ways to do this:
- Restore the database from online backup.
A wrong page number or bad checksum is detected during online backup, and
the backup will abort. This means you are assured that the damaged page did
not exist at the time of your last successful backup.
- Defragment the database with NTDSUTIL.
Offline Defragmentation of the Active Directory Database [ntrelease]
ID: Q232122
If the bad page is empty, it will be discarded from the database. The
likelihood that the bad page is empty is greater if the -1018 has never been
seen during normal operation, but only during online backup or nightly
online maintenance.
Offline defragmentation will not finish if a page in use is bad.
Therefore, if defragmentation succeeds, the -1018 will be gone.
- Hard repair the database with NTDSUTIL.
Bad pages will be thrown away by hard repair, and then the database will
try to repair the logical damage left by this hole as best it can. The
success of this strategy is unpredictable, although it works more often than
not and with minimal loss of data. Everything depends on what was on the
page.
IMPORTANT: After running Repair of the database, you should run the
Symantic integrity analysis.
Repairing a database is usually an inferior strategy compared to
restoring from backup and rolling the database forward. Repair usually takes
longer than restoration and is riskier. Choose repair only if (1) you do not
have a backup, or (2) you cannot roll forward completely from your backup
from some reason.
