RAID protection offers the basic hard drive failure tolerance to your storage systems, but it's not without its limitations. There are 2 major drawbacks of generic RAIDs - the long rebuild times and the array's vulnerability to further failure during rebuild time.
Infortrend's Intelligent DriveRecovery (IDR) technology seeks to change this, by increasing the integrity and system efficiency of a RAID system.
What is IDR
IDR Works best with RAID 6 ( Dual Parity). What IDR essentially does is - scans the drives for any media errors, recreate the unreadable sectors using RAID parity, and then relocate that data to another readable sector; all transparently to the user.
It means that IDR can silently scan and repair the array, fixing the potential data issues before they happen.
How is IDR different from a Generic RAID
Hard drives have additional blocks and a Data relocation mechanism to copy the data from a failing block to a new block. Generic RAID relies on this Drive mechanism. However, relying on the drive mechanism doesn't guarantee that there is a periodic scan to check for and correct failing blocks. Further, if the failing/failed block is beyond repair, there is data failure with generic RAIDs.
But not with IDR - The main advantage of IDR becomes evident when there is a block that's beyond repair and the drive's inbuilt mechanism fails to relocate the data. In such a case, IDR calculates the data with RAID parity and then attempts to write it to the same area ( premise here is that the block at the read error, may not have write error). If it's not able to write, it's confirmed that the block has both read and write errors and in that case, the drive is asked to reassign that block to another location.
Periodic scan for any blocks that may be failing, and the ability to calculate the data based on RAID parity, both make IDR an excellent tool for fixing data problems before they happen.
