Partition Types in a Soft Spanned Set
September 22, 2008 by Dick Correa
Filed under How To's, RAID Recovery Explained
Last time I explained the basic premise of a spanned set. I used the example of a clients RAID that contained 3 36 GB SCSI drives. In a standard set each one of the drives would use one partiton for the entire drive and then the set would be mounted...
[Read more...]Recovering a Spanned RAID Set Without RAID Software
August 27, 2008 by Dick Correa
Filed under RAID Recovery Explained
Recently it was my displeasure to work on a three drive spanned set for NT 4.0. The set was soft configured so when the boot drive went down, with all of the configuration data for the RAID on it, the RAID would not mount. In addition to that,...
[Read more...]Determining a Stale Hard Drive in Most RAIDs
August 1, 2008 by Dick Correa
Filed under How To's, RAID Recovery Explained
In my last installment I covered two of the three reasons why we do a parity check. First we want to make sure that we do not have a stale hard drive in the array. Although I did not cover how one determines if in fact a stale hard drive exists,...
[Read more...]Analyzing RAID parity
July 23, 2008 by Dick Correa
Filed under File Systems Explained, RAID Recovery Explained, SNAP Server File System
Last time I discussed how to find the RAID data offset for a SNAP OS 4.x RAID handler. To put it briefly it was just a simple matter of finding Cylinder Group zero on the first drive in the array and back tracking 48 sectors. Once the RAID data offset...
[Read more...]Finding SNAP OS 4.x RAID Data Offset
July 21, 2008 by Dick Correa
Filed under SNAP Server File System
If you are in this business long enough you will see everything, or will you? Two weeks ago I received a SNAP RAID OS 4.x for recovery. I have done a lot of these and I am pretty familiar with the data offsets, how the drives are setup, and where...
[Read more...]Check Your RAID Consistency Before A Rebuild
May 8, 2008 by Dick Correa
Filed under RAID Recovery Explained
Over the years one of the most consistent problems with RAID recovery is the rebuild. I would estimate that nearly 40 percent of the RAIDs that we cannot recover are due exclusively to the fact that a technician executed a rebuild before verifying the...
[Read more...]RAID Five Steps to recovering your data
February 22, 2008 by Dick Correa
Filed under RAID Recovery Explained
In one of my articles I tried to define the mathematics of a RAID 5 stripe and how it relates to data recovery. Using the eXclusive ORing truth table we can continue to run the array even when one drive has dropped out of the array. This...
[Read more...]