Data Recovery Raid, Determinants and Techniques You Should Know
The risk of data loss is one of the few things that each owner of a hard disk-dependent device fears and has to contend with. It is important to note that the failure of a hard disk is normally gradual, with one disk failing at first before the rest of the disks follow suit. RAID is a means of guaranteeing retrieval of data lost through the failure of one disk. RAID is an acronym that stands for Redundancy Array on Independent (previously linked to inexpensive) Disks.
Methodologies that determine how RAID works
Data Recovery Raid Determinants
There are a few data recovery RAID expressions that need an explanation to make it easy to understand how RAID works. RAID generally works through the help of various individual technologies to make sure that the data on one disk is replicated on another disk before failure. These technologies include;
- Mirroring: This refers to the storage of identical data on a number of RAID member disks at the same time. In layman terms, there is a replication of the write function over some disks as the main disk is receiving data.
- Striping: Striping refers to the dividing of a stream of data into smaller blocks of data. These blocks are then allocated various slots on the disk. This makes it easier to retrieve various portions of the data in case of sectional disk failure.
- Parity: Parity is a means through which error detection and calculation is achieved on the disk. The parity method entails assigning each data block a checksum bit. Whenever a block fails, recalculating the incorrectness of checksum bits determines the disk’s fault tolerance.
Understanding how data recovery RAID works also call for a brief on the various levels of RAID in use.
- RAID 0: This system relies on striping to provide ease of data recovery in case of sectional disk failure. Though lacking in fault tolerance, it is faster than the other RAID levels.
- RAID 1: This system relies on mirroring and requires at least 2 disks to work. It provides both fault tolerance capabilities and high speeds.
- RAID 5: This is by far the most common RAID level in use and uses both disk parity and striping. Demanding three disks or more, it offers a faster read function and a slightly slower write function than RAID 0. It is also superb for the fact that in case of a drive failure you will be able to change a disk without interfering with the rest of the disks functionality.
- RAID 6: This system uses striping but with double parity checks, which allows for two simultaneous disk failures. Requiring four disks or more at a time, the read function is as good as RAID 5’s but the writing function is way lower.
RAID Data Recovery methods
Should you face considerable data loss through RAID disks failures you can recover data from the disks manually or by use of a software.
Manual RAID data recovery
Manual data recovery on any type of RAID data disk is a long tiresome process. It also requires some technical skill to carry out. Important to note you need to start by determining the following array patterns:
- Number of disks: This is possible through hexing or inspecting the read and write log files for timestamps to determine the replication of a single batch of data rewrite.
- Disk order: This can be one through the determination of the master boot record file (MBR) in the case of hardware RAIDs or the Boot Record in the case of software created RAID.
- Block/Stripe size: For hardware RAIDs determining the block size means trying to go through the appropriate values that might be assigned to the disk. In software RAIDS, it might be a little easier since most RAIDS will have a default operating system assigned block size.
- Start offset section on a disk: In hardware RAIDs, the start of the disk marks the offset section while in software RAIDs you will need to locate the partition boot record (PBR) of the disk.
The above determinants are standard requirements for all RAIDs.
The more common RAID 5 will always call for a few other determinants.
- Parity pattern: Defining parity spots will require that you go through blocks to determine non-data storage blocks. Each non-data storage blocks denote a parity block.
- Disk sequence: determining disk sequence is one of the hardest things to do. Following up on disk sequence requires the use of a software on a separate non-RAID machine which is an expensive affair in itself. To avoid this, just label the position of your disks while they are still in use.
It is important to add that determining all the above will require lots of data reading. To stop data corruption you should engage the use of data write-blocking techniques to avoid tampering with the available data.
Software RAID data recovery
Software data RAID recovery is rather easy to carry out since you are not required to have lots of technical skills. It is also faster and way better in case of the need to ensure that data integrity and privacy is retained.
There are various software that can be used for RAID recovery but the methodology is always similar in most of them.
1. Program choice download and installation
There are a good number of data recovery RAID software in the market. Getting a handy one is not such a huge task. Follow up on reviews or ask a few techies on data recovery forums and they will lead you in the right direction. Once you have made up your mind on one, download it and install it on your computer.
2. Disk image creation
This is not a standard feature on all software but some do have it and it is a better choice since it creates an allowance for non-interruption of the main disk. For this option, you will have to choose the disk(s) you wish to scan and have the software create a disk image of the same. Though safer, it requires time so some people prefer to skip this step.
3. Choose your image or live disk
Once you are sure of the disk or image you wish to recover data from, choose it and let the software run a scan on it. Different software will always offer scan different configurations. For maximum recovery, you should always choose a full or deep scan over quick scan.
4. Recovering data
Once the scan is complete, a number of software will offer you the chance to preview the scanned results. You can then choose to save an individual file or save the whole batch of recovered files. To avoid data corruption, the recovered files should be transferred to an independent disk that is not associated with the array of disks under use at that particular time.
Professional RAID Data Recovery
In most instances, software RAID data recovery works quite well but it might not be foolproof. You might have to enlist the services of a professional data recovery RAID expert in the case of major data loss. Such corruption might arise due to fires, water logging of the disks or magnetic interruption.
Professional data recovery RAID analysts are able to use specialized tools in more dire scenarios. For lighter cases, they can carry out data recovery within a period of hours inside your premises. In more complex scenarios they might have to carry your disks back to their labs for data recovery. Lab analysis takes time in the case of complex data loss. As expensive as they come, it is worth weighing the price you pay versus the need to retain your data.