technology of data recovery
Two general types of data recovery approach is possible depending of if there is a physical damage, malfunction or any other kind of mechanical error that prevents data to be read and accessed. If that is the case data recovery gets more complicated and it is often necessary to leave it to the professional data recovery firm to do the job. If there is no mechanical or electrical damage and disk drive is working properly a software only approach can yield to good results. Basically, a specialized software program for data recovery is installed and a disk with lost data is accessed for scan and recovery. Free Data Recovery Software is such a program, that allows you to recover data from a hard drive, or other memory storage media (usb and other removable devices).
When a drive fails
Hard drive consist of multiple platters that rotate at high speeds and a very precise head that floats above surface to read information. Both platter sides (top and bottom) are used for data writing. Due to cylinder alignment problem with multi platter disks it is not possible to take a platter from a second drive and insert it on a failed drive in order to make recovery possible. If a cylinder moves even by extremely small amount disks can't line up and recovery is not possible. A partition structure usually starts at the cylinder boundaries. By knowing where cylinder is it is possible to precisely access it avoiding going through every bit to figure where partition begins at. That makes data recovery much more possible because you are avoiding a failure whenever it hits a bad block, by skipping the content and looking just for the desired partition.
This is just one example that shows how data recovery from a physical damaged or malfunctioned drive can be hard and it requires high level of knowledge and experience. If a device fails never attempt to recover data from it without a professional help. There are a lot of advices on internet that might work in some circumstances but in reality the possibility to further damage the device and permanently loose data is just too high, unless you really know what you are doing
software data recovery
Software applications for data recovery takes advantage of the fact that deleted files in Windows environment aren't really deleted at all. What happens when you delete a file is that Windows has been told that a deleted data can be overwritten by a new data if needed, but the actual deleted data is in fact intact. Whether the deleted data will be overwritten depends on how much data transfers and general disk activity has happened in the meanwhile - the more disk is used after data loss happened the less possibility will be to recover data successfully from it.
A data that reside on the surface of a drive is usually not packed in a nice, continuous blocks that contains a data stream which represents a file. Most often, data is scattered around and a single file can have bits of its data on many locations on hard drive. Technically speaking, a data is fragmented. A process of repositioning the data to make a more efficient use and speed up hard drive operations is called defragmenting. A well defragmented drive will always have a better chance for data recovery than a fragmented drive. But, defragmenting drive after a data loss will make recovery almost impossible. So a general rule of a thumb is to have disk regularly defragmented but never after a data loss happens.
about free data recovery software
Two general types of data recovery approach is possible depending of if there is a physical damage, malfunction or any other kind of mechanical error that prevents data to be read and accessed. If that is the case data recovery gets more complicated and it is often necessary to leave it to the professional data recovery firm to do the job. If there is no mechanical or electrical damage and disk drive is working properly a software only approach can yield to good results. Basically, a specialized software program for data recovery is installed and a disk with lost data is accessed for scan and recovery. Free Data Recovery Software is such a program, that allows you to recover data from a hard drive, or other memory storage media (usb and other removable devices).