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RAID 5 Data Recovery Services

RAID 5 Data Recovery Services

DTI Data can recover data from any failed RAID 5 array configuration: SAN, NAS, Snap Server, iSCSI servers and all other RAID 5 configured server storage. As data recovery for RAID 5 Virtual Machine (VMware and vSphere) is becoming more frequent, our programmers have developed tools to recover data from virtualized storage devices.  We have certified specialists and file system programmers here at DTI Data Recovery to address your VMFS recovery needs. Our programming and engineering staff has the ability to develop customized software and hardware solutions to address complex VMFS files system problems.

DTI Data Recovery offers no charge evaluations for RAID 5 data recovery services.

Utilizing custom software and hardware solutions, DTI Data Recovery is the best choice for your vital server data. Over the decades we have recovered many RAID 5 arrays that had been to other data recovery facilities. There may be instances where you have only one chance at a getting a recovery, make sure you entrust your RAID 5 to a reliable and experienced company. It may be difficult to determine which RAID data recovery company is the best choice for your needs. If you have found yourself in a situation where a company’s online resume outweighed their recovery capabilities, we may be your second chance. If a RAID 5 array has already been to another data recovery company and was determined unrecoverable, call us for a free consultation.

Common RAID 5 failures

  1. One drive is marked as bad by the RAID controller and the array is degraded but continues to run. The drive is then forced online and the data becomes corrupt.
  2. One drive is marked by the RAID controller as bad and the array is running in degraded state. The Drive is not replaced and the array continues to function. A second drive fails and the array fails. It is not clear which drive went down first and it becomes difficult to determine which drive has stale data. Unless the administrator of the array is absolutely certain which drive failed first, no rebuild should be attempted. A best practice, although inconvenient, would be to image all drive members in the array prior to any rebuild.
  3. An automatic rebuild is started and the wrong drive is used as a rebuild point.
  4. Drives are taken out of array and put back in enclosure out of order.
  5. RAID 5 controller failure.

There are many other problems associated with RAID 5 data recovery but the above are the most prevalent.

RAID 5 Data Recovery Procedures

  • All RAID 5 failed hard drive recovery is performed in our certified IS0 5 Class 100 clean room.
  • Before any utilities are run against a RAID, all the disks are imaged or cloned sector by sector.
  • We have RAID 5 recovery file system engineers.
  • Specialized software can be coded for complex recovery needs.
  • We are manufacturer authorized to open hard drives that are failed RAID 5 members.
  • We have a security audited bio-metrically secure clean room and data recovery lab.
  • All client data is held on air gapped severs. Client images and clones are held for 10 business days. After 10 business days all client data is securely wiped and clone drives are repurposed for new images.

RAID 5 Data Recovery Brief and Parity Rotations

RAID 5 uses a stripe, broken into blocks. One block in each stripe is not a data block, it is a parity block. The parity block houses the redundant data needed to run with one drive missing from the RAID array or rebuild a new drive that has replaced a failed member. Using XOR mathematics it is possible to lose one drive and still run in a degraded state, if a second drive fails the array fails as well. The mathematic technology used in RAID 5 arrays is the same used in analog modem parity bits.

RAID 5 optimizes multiple drives for greater space and allows data redundancy up to the loss of one element or drive in the RAID 5 array. There is a throughput benefit because there are multiple disks but there are some calculations that are made in order to create a parity block. Parity rotates from one drive to the next. There are several different types of parity rotation. The most common parity rotations are listed below.

  • Left synchronous parity rotation: Data blocks follow parity blocks in sequential order. Parity blocks move from the furthermost right to left. When the parity rotation has completed, it starts again from the furthermost right to left.RAID 5 Left Synchronous Parity

 

  • Right synchronous parity rotation: Data block follow parity blocks in sequential order. Parity blocks move from the furthermost left to right. When the parity rotation has completed, it begins again from the furthermost left to right.RAID 5 Right Synchronous Parity
  • Left asynchronous parity rotation: Data blocks do not follow parity blocks. Data blocks move sequentially from one drive to the next skipping parity blocks. Parity blocks begin at the furthermost right and move left. When the parity rotation has completed, it begins again.RAID 5 Left Asynchronous Parity

 

  • Right-asymmetric of forward parity rotation: Data blocks do not follow parity blocks. Data blocks move sequentially from one drive to the next skipping parity blocks. Parity blocks begin at the furthermost left and move left. When the parity rotation has completed it begins again from the furthermost left.RAID 5 Right Asynchronous Parity

 

  • HP RAID 5 left synchronous delayed parity rotation: All Hewlett Packard RAID 5 arrays use delayed parity rotation. The delay in parity for all HP RAID arrays is 16. The parity rotation moves in the standard left synchronous rotation but is delayed for 16 rotations through the total parity rotation from the furthermost right to left and begins again until all rotations have completed throughout the total space allocated to the RAID array.RAID 5 Data Recovery

RAID 5 Meta Data: Some RAID 5 servers use metadata to identify array members or drives and other information the controller uses to maintain and optimize the RAID 5 array. In terms of RAID 5 data recovery this means there is an offset from the beginning of each drive to where the RAID array or the data partition actually starts.RAID Controller Metadata

 

RAID 5 arrays using LVM (logical volume manager) NAS devices using Linux variants EXT2, EXT3, EXT4, XFS have sector offsets.

Our RAID 5 engineers have decades of experience and are well versed with all standard and non-standard RAID 5 variations.