The evaluation of a RAID system recovery is actually the combination of two very important steps:. The first, and the longest, is the reassembly of the matrix. When the Ontrack Data Recovery engineers reassemble the logical system, they thoroughly research how the data is organized across all disks.
They then know the order of disks and the arrangement of data blocks and parity blocks. This investment in time is necessary to determine the original configuration and obtain a quality recovery,.
The second step is to work on the logical file system. Current enterprise log file systems are extremely complex. If the RAID array is down, there will be thousands of errors within the file system.
Ontrack Data Recovery engineers will verify and confirm that the matrix is structured correctly before copying any data. This extra step guarantees a quality recovery. RAID: RAID is a technology that supports the use of 2 or more hard drives in various configurations for the purposes of achieving greater performance, reliability and larger volume sizes through the use of consolidating disk resources and parity calculations.
Parity: A mathematical calculation which allows drives within a RAID array to fail without the loss of data. You can remove anyone of the letters from above and work out its value from the 2 remaining.
This is obviously a simplistic way of describing it, to fully understand it in a RAID sense, knowledge of binary and the logical XOR expression is required. Mirroring: The data from 1 or more hard drives is duplicated onto another physical disk s. Striping: The method that data and parity can be written across multiple disks. In the example below the data is written across the drives in a sequential order until the last drive, it then jumps back to the first and starts a 2nd stripe.
Block: A block is the logical space on each disk where the data is written, the amount of space is set by the RAID controller and most commonly would be 16KB to KB in size. The data will fill up the space until the limit is reached and then move onto the next drive, until the last drive when it will jump to the start of the next stripe.
There are four main styles of symmetry, which one is used depends on the RAID vender. Some companies also make proprietary styles depending on their business needs.
It is a spare disk which can be used in place of the failed one. In case of data recovery, the time for recovery takes place on the size of the disk drive. Double parity offers additional time for rebuilding the array without the data being at risk if single additional drive fails, while the data recovery through rebuild is happening.
RAID 10 will also have fault tolerance and will also have redundancy. It will have the splitting of data feature seen in RAID 0 level and will also have mirroring feature seen in raid 1 level. RAID 10 array can recover from multiple and simultaneous hard drive failures and is ideal for high end server applications. This level is a combination of raid 0 and raid 1 level and is used in imaging applications meant file servers.
It offers high performance and reduces emphasis on reliability. In this JBOD raid level, the array of hard disks is made to appear as a single disk system. But there is no raid level implementation on it, which results in lack of fault tolerance. RAID technology is to offer redundancy for the stored data, but sometimes the servers, which are having RAID as protection, can also face failures and data loss issues.
This is possible by the following ways-. When the RAID technology fails in the data center, which is not uncommon, IT administrator must make sure that, they must not take any hasty decision. In the case of logical problems, the work gets difficult on the analysis of the file system and the correctness in working on it. In the case of Mirrored RAID levels, the data can be mixed and matched to reconstruct a good drive, from the good sectors of the two drives. Data rebuilding can be done from the striped RAID schemes which use parity.
This strip level rebuilding of data is easier than the per drive basis. If they are multiple bad sectors in more than one drive, then they have to be corrected individually.
If data goes missing, then the RAID controller will take a disk off-line when it fails and is operated in degraded mode for reconstruction of lost data from a missing disk and that too on demand. If all this seems to be too tedious then here is a solution. Nowadays, Raid recovery software is available and is being developed and offered by many companies. This ensures that the valuable data in the data centers, protected by RAID technology can be recovered without much struggle, in case of unexpected failures.
Those who are unfamiliar with the concept of RAID technology, it may be sounding like a daunting task to implement it. But the benefits offered by its implementation will surely justify its technology, at the time of disaster recovery.
Technical Education. Software Raid vs. Share on linkedin. Home Engineering. RAID Explained. Linux , Novice , Storage. Elle Krout May 19, 5 Minute Read. Parity A parity bit is a bit added to the end of the data string used for error checking. Recommended Get more insights, news, and assorted awesomeness around all things cloud learning. Kesha Williams Nov 11, 23 Minute Read. Nigel Poulton Nov 10, 11 Minute Read.
Sign In. A Cloud Guru. At that time, you should figure out the reasons behind the issues and fix them as soon as possible. Last but not least, RAID systems are able to work much faster than a single drive. Therefore, the transmission rate is improved.
Users can achieve better disk performance. Shirley Zhang is a data recovery expert in DataNumen, Inc. For more information visit www. Your email address will not be published.
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