Restoring NDS from Tape Backup: Proceed with Extreme Caution
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Posted: 23 Dec 2003
If you're thinking about restoring NDS from a tape backup, you need to read this next sentence very carefully. The NDS database should not be restored from tape except in cases of extreme disaster, and the entire old NDS tree should be eradicated before doing so. Here's why.
A tape backup does not overwrite the old database with a copy like that on the tape. Instead, the NDS restore process will attempt to recreate all of the objects that existed when the backup was performed.
If a restore is performed under disaster recovery conditions, in which the original NDS database has been destroyed and NetWare reinstalled, then the NDS objects and attributes stored on the tape are being added to the minimal NDS tree provided by the NetWare installation process, resulting in a tree that is the same as the one that was saved to tape.
If, however, an NDS tree still exists on the server to which the restore is being performed, a tape will attempt to append to the old tree, rather than overwrite it. In the best possible case, the restore process will have no visible effect at all. The worst possible case will result in additional, unwanted objects being added to the existing NDS structure, leaving the old corrupted structures intact, and possibly adding additional corrupt elements.
Also be aware that the trustees of Root are not restored during a restore of NDS from tape. Admin will be the only user with full trustee rights to Root after a tape restore, even if other users had an explicit trustee assignment to Root. However, security equal to rights will be restored. If a user was security equal to admin, then the user will have the same rights that admin has- which is usually full rights to the tree.
Anyone have anything to add about restoring from tape? We'd love to hear from you...
- Backing Up and Restoring NDS
- Restoring NDS on NetWare after a Hardware Failure
- Preparing to Back Up (SBCON)
OK- so we now know the horrors of restoring NDS/eDir from tape. Restore from tape = bad, unless you really have no other choice.
How about a link to a TID on the correct procedure? It's fine to say "don't do it this way." To be complete, you should also say "Here is the step by step procedure to do it correctly."
Editor: Good point, Marlo. We've added some documentation links now. Thanks for the suggestion.
Under disaster recovery conditions, you may need to restore a backup of each partition in the tree to the server to give it a full copy of the tree. This is where the layering effect comes into its own - if you have no 'live' system left, without this you would need the same number of servers as you have in partitions to restore sections of the tree - not a good scenario in a big tree!
Don't use a tape. Check out DeTroubler. We've been using it since 1999.
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