Disaster Recovery?

M. Grochmal asks: "A three-alarm fire at Southern Maine Technical College burned through the Computer Technology and Technical Graphics departments. We have salvaged most of what we can, but cannot return into the building until the asbestos risk decreases. The hard part now is rebuilding the networks in another building. The schedules have been rearranged, many of the department students and faculty are volunteering to relocate salvageable computers, as well as install/configure the new computers that will be arriving in the next day or so. On top of that, we have to rebuild the Netware servers, restore from backups, and get them networked again. I was wondering how other Slashdot readers were able to recuperate from unforeseen damage to their work (and learning) environments. You can read about the fire here and see what the schedule is. Wish us luck."

Comments

Re:NDS and the 3 day rule

[AndyDeck]

Bull. Utter crap. There is ABSOLUTELY NO reason that you would be forced to restore your NDS within three calendar days or rebuild your tree. Where did you get your information? The only three day limit I know of is a recommendation that if a server was going to be offline for more than this time, it might be better to remove it from the tree. This does keep NDS updating cleanly, as a partition can't advance its timestamps to the current time until the changes have been seen by all replicas.

That said, of course you should have had offsite replicas of each partition. With offsite replicas (or at least replicas on servers that didn't get destroyed) you can remove the crashed servers, still have access to your NDS resources (IDs, passwords, etc), and then re-install the crashed servers to the tree later.

But with or without offsite replicas - three days makes no sense. If the whole tree is involved in the disaster (all servers containing replicas of the tree are gone), it doesn't matter how long it takes you to begin NDS recovery. If the whole tree is not involved, but ALL replicas of a partition are, you may have isses with external references and subordinate reference partitions until you've completed recovery - but nothing that would require 'rebuilding your tree'. If all replicas are not gone, you do NOT have a problem, just a challenge :) Follow the TIDs and you will be fine.

Netware crashed server recovery has been interesting over the years. Netware 5.x & NDS8 removed the old DSMaint NLM that could preserve server references, so until the recent release of the XBROWSE program, the only clean way to quickly recover from a crashed server while preserving server references was to hang on to an old NW4x box to run the DSMaint process.

Recovering NDS from real disasters can be... challenging. If you don't know what you are doing, you *can* really mess things up. Be careful and you'll be fine.