Cyclic Redundancy Error

You must have noticed the ‘cyclic redundancy error’ several times when copying data from any external storage device like a DVD to your computer hard drive. Once this message shows itself, you find that the copying of data ceases and the transfer of the file cannot be completed. Why does this happen? What does a cyclic redundancy error mean and how can it be fixed? That is what you will find explained in this article.

For many days, I was under the impression that the arising of a cyclic redundancy error means that data transfer is not possible. However, that is certainly not the case. You can still carry out transfer of data using some techniques that I share in the text below. First let us understand what is cyclic redundancy error and why does it arise.

What is a Cyclic Redundancy Error?

A cyclic redundancy check is carried out to ensure the integrity of data being transferred from one data storage device to the other. In mathematical jargon, cyclic redundancy error is also known as ‘polynomial check sum method’. Digital data verification during transfer, is the primary objective of implementing the cyclic redundancy check algorithm.

As you start making a data transfer from one destination to the other, a cyclic redundancy code is created and a small bit of information is attached to the data being transferred. On reception of each piece of data, the code is again calculated according to the sequence of attached bits connected with the data. If this code is exactly similar to the one that is generated at the source destination, then the data has suffered no damage en route to the destination. On the other hand, if this code is not the same as the one generated before, it leads to what is known as a cyclic redundancy error.

There are many reasons why a cyclic redundancy error in hard drive may arise. It may be due to creation of bad sectors in the region where the data was stored or due to physical damage at that location. Another possibility is corruption of data. A cyclic redundancy error in DVD may arise due to damage to any of its grooves. Is there any way out of a cyclic redundancy check error? Let us find out in the next section if data recovery is still possible in this case.

How to Fix Cyclic Redundancy Error

To fix cyclic redundancy check errors, first the cause of the anomaly needs to be diagnosed. When such an error crops up during data transfer, either you have a problem at the source or at the destination in the form of a data corruption problem or bad sectors in case of a hard drive. To check if the problem lies at the destination on your Windows machine, do the following. Go to command prompt on your Windows PC and type in as follows:

C:\>CD (Location of File)

C:\(Location of File Folder)>copy (Name of File) NUL

This command will help you investigate whether a problem lies with the destination. If the command gets executed successfully, then there is a problem with the hard drive destination where you are copying the data. So change the copying location and run a checkdisk to look for bad sectors on the hard drive.

On the other hand, if the command does not execute successfully, you have a problem at the source. The data is probably corrupted at source. Normally if a cyclic redundancy error crops up in Windows XP, Windows Vista or Windows 7, the data transfer ceases. However, using the following command, you can retrieve whatever data that is non-corrupted, even though some parts are damaged. Open command prompt again and type the following.

C:\>CD (Location of File)

C:\(Location of File)>xcopy /c (Name of File) (File Destination)

This command will let you copy whatever data that has been left uncorrupted. This is one of the simplest tricks that you can learn from a computer repair technician. Other than this simple command, what you can do to fix cyclic redundancy check errors is run a scandisk function (to check for bad sectors) or get a good data recovery software that can do this for you. There are many hard drive data recovery software programs for you to choose from.

Hope this article has cleared most of your doubts regarding what is a cyclic redundancy error and how can it be fixed easily. As I said before, if the storage device has undergone extensive physical damage, the data may be almost irretrievable. However, using the above mentioned technique, you can still salvage whatever data that is non-corrupted and left intact.