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Realities of RAID: Data Loss Still ExistsOctober 24, 2006
By Jim Reinert RAID (Redundant Array of Independent Disks) technology has been around for many years, and has proven to be a reliable and convenient storage option. More and more companies have turned to these systems to manage their vast amounts of data since they not only boast significantly better reading/writing speeds over single drive servers and better fault tolerance should a drive fail, but also because they offer far superior data protection. However, as is the case with all technology, nothing is fool proof, including RAID devices. Redundancy Equals ProtectionRAID systems are great for data protection because they allow data to be written to multiple hard disk drives so that a failure of any one drive in the array does not result in the loss of any data. RAID systems also increase the system’s fault tolerance – that being the system’s ability to continue operating when presented with a hardware (or software) failure – as should be experienced when a hard drive fails in one of the redundant configurations of RAID. Because RAID systems offer this built-in protection and businesses are focused on finding solutions that protect their data and help them avoid the downtime that accompanies data loss, most businesses rely on them to house their mission critical data such as financial data and business system data (email, back office, large database application data). Redundancy Isn’t Fail SafeBut what happens when there is a major issue with the RAID system that results in the data becoming inaccessible? Although RAIDs are specifically created to guard against data loss, they are still susceptible to total system failures if multiple drives experience problems at the same time. Other problems can occur when RAID controllers don’t recognize the drives in the array or if a drive is removed from a hot swappable drive bay and a new one is replaced in the wrong order. The bottom line is that, just like single hard drive systems, RAID systems can also experience problems that can lead to data loss – the difference is, with a RAID failure, the problem can literally cripple a business or halt operations since the data stored on the RAID array is usually business critical. Unfortunately, after experiencing a RAID malfunction, many businesses give up hope if they are told by their own IT staff, vendors, technical support or consultants that their data is inaccessible with no chance for recovery. When RAID problems happen, most think it is the end of the line for that data – if the RAID is broken, there is no way to get the data back. This simply isn’t true and businesses need to know that they do have options if their RAID system stops working. Data recovery providers can fix broken RAIDs, but the key is to work with RAID recovery experts to ensure that the most critical data has the best chance to be saved. Data Recovery & RAIDOften times, IT staff will attempt to fix the system by relying solely on the original RAID configuration, documented administrative procedures, or will attempt to force a RAID controller or drives in a RAID into a particular configuration which usually results in even greater damage to the customer’s data. However, RAID experts know that rather than forcing normal procedures, one should figure out the RAID “by hand,” which means that they look at every sector of data across all of the drives in a system to put it back together. Specifically, they don’t rely on the original RAID configuration because it may have flaws in it. By rebuilding the distributed data blocks, drive order and data symmetry manually, even the most challenging RAID system can be recovered. Experienced Engineers even have the ability to work on RAID systems if the original hard drive has failed by reconstructing the RAID virtually. More importantly, some experienced companies can often recover the RAID system in the field remotely via Internet or dial-up connection so the customer doesn’t have to pull out drives and racks for shipping. This is an important benefit as it allows the fastest possible recovery for critical data – often times getting businesses back up and running in only a matter of hours. In this first-hand account, Marc Valle from GBDH Design Group, an architectural-engineering business based in Sacramento, Calif. says they were in the process of transferring data to a new server when one of the drives in the RAID system failed. As such, they were unable to have a complete back-up prior to the operation. With mission critical data lost, Marc was panicked that the company would not have been able to continue in business without the data. After using a recovery service that was inexperienced in RAID arrays, they turned to the engineers at OnTrack who were able to recover 99 percent of the data and keep them operating. It is also important to note that an advantage of data recovery is its ability to get back the most recent files versus the most recent backups – a crucial distinction since RAIDs often store the highest value data. About the AuthorJim Reinert serves as senior director of Software and Services for Ontrack Data Recovery. In this position since April 2004, Reinert handles the technology and business development and product line management of the recovery services and software business lines. With Ontrack since 1987, Reinert has held a variety of positions with the company, including software engineer, engineering manager and Director of Technology. Reinert holds a BS in Electrical Engineering and Computer Science from St. Could State University.
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