Large scale storage solutions, such as RAID 5 were at one time the preserve of the enterprise level customer, and rarely even seen in the medium sized business arena. Since the price of data storage has tumbled, while at the same time the capacity has increased, even a small business which requires a large storage capacity, can now afford to use a RAID 5 array.
With the patent for RAID 5 array data configuration being filed in 1986, this type of array has been in use for many years, with many examples requiring data recovery by DiskEng. We have extensive experience and in-depth knowledge of data recovery from RAID 5 arrays, ranging from the simplest 3 disk configuration, right up to architectures with tens of drives used in a single server system.
Speed Versus Data Redundancy
By using a RAID 5 array, there is an inherent built-in speed increase for each read/write operation, due to distributing the data across multiple disks. The built-in redundancy, whereby the parity of each data stripe has to be recalculated on each write operation has a small, but detrimental effect on the ultimate speed possible.
The RAID 5 array was for many years seen as the perfect compromise, providing redundancy, without causing a serious decrease in the overall speeds achievable. Many consumers were under the mistaken belief that the built-in redundancy meant that it was not necessary to have any backup strategy.
Rebuilding RAID 5 Array
When a single disk fails a RAID 5 array will enter a mode known as degraded mode, but is still able to operate, although the underlying data transfer speeds will be affected. It is important that a RAID 5 array is not allowed to continue running in this state for any length of time, as a further disk failure could be imminent, which would result in the complete failure, which would take the RAID array offline.
The parity data in a RAID array allows the data from a missing drive to be recalculated as required. It is therefore possible to replace the failed hard disk drive, and initiate a rebuild, which should recreate the data onto the new drive. With the increased drive capacities now in the terabyte range, the likelihood of another failure occurring during this process is considerably higher than it was 10 years ago.
RAID 5 Array Data Recovery
When a failure occurs in a RAID 5 array, it is important not to panic, and make any mistakes which could risk the integrity of the data stored on it. If you RAID 5 array should go offline as the result of a rebuild failure, another hardware fault or a logical problem, you should power the server down and contact a professional data recovery company, such as DiskEng, who have the in-depth knowledge and experience of both the RAID architecture and the file system stored on the array.
Ill-considered attempts to force the RAID array back online, or attempting to swap further drives following a rebuild failure, could result in further damage or in the worst case a total loss of data. It is important to understand the importance of the data, and how if it were lost, what the consequences would be for the future of the company.