I have a laptop hard drive, that initially failed to boot. I took the hard drive out and connected it to my PC and was able to see the files on one of the partitions (D Drive). The then connected my external hard to copy the files over, but the pc crashed. The pc was restarted and when i try to connect the laptop external hard, it does not appear in My Computer. I have checked under disk management and the drive is shown an unallocated, when i try to initialize disk, I get an "Data Error CRC" message and The drive size is 320GB and is a seagate Momentus 320 GB. Is the data recoverable?
CRC errors tell us that the hard drive your files are stored on is damaged. A CRC error is generated when the hard drive is instructed by the computer to read a file from the hard drive but fails. The file to read is actually stored as a sequence of 0's and 1's and when the hard disk has read it successfully the file is presented to the user on the computer. When the file can not be read from the disk, one of the causes is a CRC error.
CRC stands for Cyclic Redundancy Check and is a checksum the computer makes of the data it has read. If the checksum is wrong the computer knows the information has been read incorrectly and it will try to read it several times more until eventually either succeeding or giving up. People with CRC problems on their hard drives will notice that file access takes a long time and their computers run very slowly.
The answer is to either get a data recovery company to get the files off of your CRC damaged hard drive, or if the data on the drive is not valuable to you, just go and buy a new hard drive. Throw away a drive that has CRC problems as they are never going to get any better, just worse. Having a hard drive with CRC problems is an accident waiting to happen.