RAID RecoveryTechFusion Knowledge Center
Due to the highly technical nature of RAID recoveries, an important step to take when choosing a data recovery provider is to ensure that the provider has the capacity to take on large and highly complex recovery jobs. Many data recovery providers do not have enough resources or expertise to handle a successful RAID recovery.
TechFusion has been working with RAID systems since their entrance into the consumer market. Our experienced technicians can address failures of all types, including multiple disk failure, logical failure, and file deletion. RAID recoveries are among the most challenging in the industry, due to the resources and time required to work with multiple disks of often large sizes. In many cases, each disk in the array needs to be repaired and imaged, an exhaustive and time consuming process in and of itself. Once working images of each disk are available, our engineers begin the highly technical process of logically reconstructing the RAID system. From there, our specialized recovery process can begin.
TechFusion uses advanced, proprietary techniques
to repair, recover and rebuild inaccessible data from all types of RAID systems and failure conditions.
Any RAID level, RAID controller or RAID architecture
Any hard drive type, make or model
All causes of data loss — including data loss resulting from human error, natural disasters, power loss or surge, logical or physical failures and invasive viruses.
First Aid for RAID: What to Do When Loss Occurs
Note: Attempting to recover a RAID without an experienced data recovery specialist can put your critical data at further risk. When hardware malfunction is a component of the problem, permanent destruction of data can occur with failed recovery attempts. Do not attempt to repair or rebuild your RAID array. If done incorrectly or with the wrong stripe block size or disk order, this may corrupt your data permanently.
When data loss occurs, power down the system properly as soon as possible. Do not simply pull the power cord, as this can result in further data loss.
Record as much of the failure circumstances as possible. Was a file deleted? Was a drive replaced? Who did it, and when? Each of these pieces of information are exceptionally useful to the recovery engineer.
Record key filenames and folders, with applicable extensions. This will allow us to target our recovery efforts.
If failure occurred after replacing a drive, bring the old drive to your recovery engineer. Do not recycle or destroy it. The information on these old drives is often key to the recovery effort.
Be sure that each drive is clearly labeled, and that each drive bay is also labeled. Do not remove drives from the array without a proper label.
To prevent catastrophic loss, actively monitor your array for abnormal mechanical sounds, slow access times, missing files and other atypical behavior. As always, keep a backup available. Do not make significant hardware or software changes without a current backup on hand in case of failure.
Common RAID related problems we help with regularly are:
RAID controller failure
RAID array or volumes that won’t mount
Multiple drive failure (or multiple drives go offline)
Partition Corruption or Damage
Lost RAID configuration
Faulty hard disks in RAID Array
Configuration damage or corruption
Addition of incompatible drives
Drive not detecting in BIOS
Media surface contamination and damage
Windows Blue-Screen Errors, Cannot access files.
Viruses or malicious intent
Software or operating system upgrade
Computer virus and worm damage
Unable to start server
Unable to boot into the operating system
Failed hard disk(s)
The time needed to recover data from a RAID array can vary depending on the brand & model of the RAID Controller, RAID configuration, file system type, the problem with the hard disks, ability to locate spare parts if needed and the condition of the data in RAID Array we receive the disks in.
Techfusion Raid Recovery recognizes all imaginable configurations of various types of arrays, including:
All the disk devices are organized alternatively so that blocks are taken equally from all disks alternatively, in order to reach higher efficiency. Since the probability of finding a block of a file is identical for all disks, there are force to work simultaneously thus making the performance of the Meta disk almost 10 times that of a single disk.
In this mode, the goal is to reach the highest security of the data. Blocks of data are duplicated in all physical disks (each block of the virtual disk has a duplicate in each of the physical disks). This configuration provides 10 times the reading performance of a single device, but it degrades writing operations. Read operations can be organized to read 10 blocks simultaneously, one from each device at a time. Similarly when writing 1 block it has to be duplicated 10 times, one for each physical device. There is no advantage in this configuration regarding storage capacity.
In this mode the ultimate goal is to balance the advantages of the type RAID0 and RAID1. Data is organized mixing both methods. The physical 1 to N-1 are organized in striping mode (RAID0) and the Nth stores the parity of the individual bits corresponding to blocks 1 to N-1. If any of the disks fails, it is possible to recover by using the parity information on the Nth hard disk. Efficiency during read operations is N-1 and during write operations is 1/2 (because writing a data block now involves writing also to the parity disk). In order to restore a broken hard disk, one only has to re-read the information and re-write it (it reads from the parity disk but it writes to the newly install hard disk).
This type is similar to RAID 4, except that now the information of the parity disk is spread over all the hard disks (no parity disk exists). It allows reducing the workload of the parity disk, that in RAID 4 it had to be accessed for every write operation (now the disk where parity information for a track is stored differs for every track).
Block-level striping with double distributed parity. Provides fault tolerance from two drive failures; array continues to operate with up to two failed drives. This makes larger RAID groups more practical, especially for high-availability systems. This becomes increasingly important as large-capacity drives lengthen the time needed to recover from the failure of a single drive. Single-parity RAID levels are as vulnerable to data loss as a RAID 0 array until the failed drive is replaced and its data rebuilt; the larger the drive, the longer the rebuild will take. Double parity gives time to rebuild the array without the data being at risk if a single additional drive fails before the rebuild is complete.
Striped sets in a mirrored set (minimum four disks; even number of disks) provides fault tolerance and improved performance but increases complexity. The key difference from RAID 1+0 is that RAID 0+1 creates a second striped set to mirror a primary striped set. The array continues to operate with one or more drives failed in the same mirror set, but if drives fail on both sides of the mirror the data on the RAID system is lost.
As there is no basic RAID level numbered larger than 9, nested RAIDs are usually unambiguously described by concatenating the numbers indicating the RAID levels, sometimes with a “+” in between. RAID 1+0 – mirrored sets in a striped set (minimum two disks but more commonly four disks to take advantage of speed benefits; even number of disks) provides fault tolerance and improved performance but increases complexity. This is the best option for databases.
RAID 60 combines the straight block-level striping of RAID 0 with the distributed double parity of RAID 6. (A RAID 0 array striped across RAID 6 elements.) It requires at least eight disks and can survive the loss of two drives in each of the RAID 6 sets without any data loss. Although high in cost and complexity, when data security is concerned, performance and fault tolerance is quite superior.
RAID is NOT Data Backup!
A RAID system used as a main drive is not a replacement for backing up data. Data may become damaged or destroyed without harm to the drive(s) on which they are stored. For example, some of the data may be overwritten by a system malfunction; a file may be damaged or deleted by user error or malice and not noticed for days or weeks. RAID can also be overwhelmed by catastrophic failure that exceeds its recovery capacity and, of course, the entire array is at risk of physical damage by fire, natural disaster, or human forces. RAID is also vulnerable to controller failure since it is not always possible to migrate a RAID to a new controller without data loss.
RAID drives can make excellent backup drives, when employed as backup devices to main storage, and particularly when located offsite from the main systems. However, the use of RAID as the main storage solution cannot replace backups.
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