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Monday, October 5th 2009

12:25 PM

Software for RAID data recovery

RAID Capable Data Recovery Software.

If you are searching the web for RAID capable data recovery software then this probably is because you are experiencing a RAID issue that prevents you from accessing the data on the array. Two common problems are: the RAID controller failed -or- while the controller still fuctions, it stopped recognizing your array.

To be able to recover data from such a scenario, data recovery must be able to virtualize the array, because recovering data from the separate disks will render all files that exceed the stripe size corrupt. In case the file size exceeds the stripe size, the data recovery software has to be able to figure out the locations of the different pieces of the file on the different disks.

The majority of the data recovery software on offer unable to do so, even though they claim to be RAID 'compatible'. And indeed they are RAID compatible as long as the array iself is intact. As long as the array is intact it will present itself as a single disk to the data recovery software and the software can treat it as such. In fact there are only a few data recovery software vendors offering software that is capable of virtualizing an array. DIY DataRecovery's iRecover happens to be one of the oldest software titles that includes this capability.

There are 2 categories for software that can virtualize an array:

1. Software in the first category can virtualize an array as long as you can tell it what the array looked like. So, if for example your RAID 0 controller died and you are unable to replace it, you need to tell it the disk order, the stripe size and in some cases the offset. If a RAID5 controller died it becomes a tad more difficult because in addition to the above you will need to tell it about the parity-rotation. The more member disks in the RAID5 array, the more complex the situation.

2. Software in this category is capable of determining array parameters automatically. Basically all that is requested from the user is that he points the software to the disks that used to be array members. And again in this category there are different approaches to the problem:

(a) There is software that scans the array members and tries to figure out the different array parameters on its own.

(b) The other type relies on a database with known settings for the different controller brands and types.

And yet another difference that can be found among software that is able to virtualize RAID arrays (automatically or manually) is in the way that they allow you to recover data from the virtualized array: On the one hand there is software that will write the entire virtualized array into an image file. You will need a separate piece of software to extract data from the recovered array. On the other hand is the software that combines RAID virtualization with a file browser from which you can select the files you want to recover from the array. Note that the software in this sub category is often also capable of writing the entire array to an image file. 

software manual  automatic    reconstruct   file browser image price ($) remarks
FileScavenger x   manual x x 185 $85 for RAID 0 only
Runtime   x scan   x 99  
R-Studio x   manual x x 79.99  
iRecover x x scan x x 89.95 best value!
RecoverMyFiles   x scan x   99.95  
DiskInternals x x database x x 249  
Getway x x scan x! x 179 ! read-only

red - only option available; for example, only automatic reconstruction vs. automatic AND manual.

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