Data recovery, by definition, follows innovations in the storage industry. After all, it is impossible to learn how to recover something that has not been invented yet. On the other hand, the recent trend is that the tasks data recovery faces are becoming more and more complex; moreover, some of these tasks are just fundamentally unsolvable. (Learn more in Disaster Recovery: The 5 Things That Often Go Wrong.)
Complexity and Big StorageBig storage takes more time to extract data, since you need at least to read and copy the entire data capacity. For example, simply reading all the data from a 2 terabyte disk takes about 10 hours given that the average read speed is 60 MB/s.
On the other hand, big storage requires new storage technology. To get storage of several terabytes you can use RAID technology. For an effectively functioning storage of dozens of terabytes, you need schemes combining RAID fault-tolerance and the efficiency of, say, block allocation algorithms of the file system driver. In practice, something like that is implemented in ZFS from Sun Microsystems and in Storage Spaces from Microsoft. The second option is a big RAID of uncommon layouts, such as RAID 60.
Recovering data in the past, whether from a camera memory card or regular hard drive, all you needed was file system recovery. Nowadays, dealing with a complex storage system consisting of several physical disks, first you need to recover your storage configuration (i.e. how separate disks work together to create a single storage). Only then can you proceed with a file recovery.
Storage configuration recovery is a complex, non-trivial task with a relatively modest chance of success. Even in the case of successful recovery, the task is very time consuming, so often it is easier just to dismiss the case as unrecoverable. In our practice, we once dealt with a failed 50 TB Storage Spaces pool, for which our recovery estimation was two to three months (note that simply reading 50 TB of data two times would take 40 days). When the client heard about this, he outright refused the recovery attempt, admitting the case was unrecoverable.