Sunday, 14 November 2010

Why do we need as much information as possible?

Once there was a discussion on one of the repair forums, and one poster said something along these lines

The only information needed to recover a RAID are the RAID disks themselves. If the recovery lab asks something like controller model, they are not a professional outfit.

This guy has some merit. If you can get your hands on the actual drives, you do not really need anything else to do the recovery. This is true for the recovery lab, which works with the actual disks (or images thereof). When we are debugging our RAID recovery freeware, there is one significant disadvantage. The actual disk images are always cost-prohibitively large to transfer, so we had to figure the problem out without these.

Lacking the images, we still have our test data sets, crash dumps, whatever, but the customer description of the problem becomes more important.

Consider the following problem report, just for an entertainment purpose:

We were running XP the software RAID5 volume holding the data failed. The array is 4x 1TB WD whatever model hard drives. The hard drives were verified separately with WD Lifeguard and tests returned no errors. However, Windows refuses to mount the array and ReclaiMe Free RAID Recovery fails to produce proper output.

Now what is the problem with the recovery? (select whitespace below for an answer).

There is a discrepancy between two statements 1. running XP and 2. using RAID5. They must have been using RAID0, because XP does not support software RAID5.

This illustrates the importance of all the details perfectly.

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