There was an issue when your computer read information from the hard drive. A calculation failed to provide results that matched the “check” values included on the hard drive alongside the information that was being read. This could be due to a number of different things, but only one of those things will mean that your hard drive is near death.
Each block (sector) of information has a check value called a cyclic redundancy check (CRC). In the event that a sector is read from the hard drive and the data contained within does not have a valid CRC then this is reported by the drive as a cyclic redundancy check error instead of providing incorrect data.
chkdsk /f /r as a first response. Chkdsk /f /r may repeatedly attempt to read the same sectors on a hard drive which may contain bad sectors. Using this command can also cause relocation or deletion of files when attempting to repair the file system. Therefore, if there is data that is important to you, make sure to back up/copy the data before using this command.As part of writing data in each sector, the hard drive generates (and writes) a Cyclic Redundancy Check (CRC), a number that can be generated based on the content of the data. During reads of sectors, the drive will regenerate a CRC for comparison with the one originally generated and stored during the write process. If these two values do not match, then the data being returned by the read operation may not have been the data written to disk; as such, rather than allow the data to flow through to your application silently, the hard drive will raise an exception (a CRC error).
The fact that this behaviour occurred is correct. This is a reporting method, not a diagnostic tool, which is why the same error can result both from having a marginally bad cable and from having a failing or dead platter.
Cable or connection. If you are using a marginal SATA or USB cable, then whatever information is being sent from the hard drive may be corrupted during transmission. At the receiving end, the drive will report a CRC error when the data received does not match the data sent. This is free to test. Try swapping cables and ports to determine which of these two options is causing the problem. For external enclosures, this type of issue occurs quite often. The USB bridge inside an external enclosure may also start to corrupt the data as it fails. Bad sectors: the physical area on the disk cannot store data reliably anymore. Bad sectors are the most common failure with an internal drive and they tend to spread to other areas. File-system corruption: in this case the file system’s index (the location of data) becomes damaged but the actual data remains intact.
Patterns tell you a lot: if an error never comes back then that’s likely going to be a one-time (transient) issue. If the same problem comes back again & again, if there are multiple problems occurring at once, or if they’re happening in very large files, those indicate issues with the disk surface.
When you run “chkdsk /r” you’re asking Windows to read every single sector on the disk in order to find out where all the bad sectors are. This can take hours; this is exactly what drives a failing disk further down the road towards total failure. In addition, as part of reading every single sector, chkdsk has to act like a file system repair tool, so it’ll delete any entries from the directory tree that it can’t resolve & move data around to get everything organised properly. It does great things on a good disk that has some small level of corruption. However, when you have a disk that has increasing numbers of bad sectors (a spread-out, not yet complete failure), running chkdsk turns many recoverable situations into many worse situations.
First of all, take copies of your essential documents and then move on to those less important, with the knowledge that some files may fail to copy during the transfer process. Now use each of these options to determine which fault type you are experiencing. Change the cable and try different ports and computers. Listen to the hard disk as you do this. Only once your files are safely copied should you let any repair tool near the drive.
When it comes to recovering your faulty hard drive, we will image what’s left (read-only) of your original files beyond the ‘bad’ areas and rebuild your system from there. The cost of an individual drive to be imaged is from £300 +VAT with a free 48-hour diagnostic, and in most cases you only pay if we recover your data.
A sector has been read by your computer and when it checks against the stored checksum for that sector, the checksum fails. So essentially what you get is not what was originally written. In fact, it is simply the drive saying it knows it’s got something wrong here but it’s not giving it to you. It is a report rather than a diagnosis; hence why the same error message can mean either a dodgy cable or failing platters.
No. It can also be a marginal cable (a cable going out), a faulty USB bridge on an external hard drive or file system errors. Try swapping cables and ports; this will cost you nothing and can resolve many of the issues especially on external drives.
Not as a first step. When using a failing disk, running chkdsk /r can cause stress by reading every sector (this could take hours). It may also either move/relocate/lose data to get the filesystem correct. First copy all files off of the disk before attempting to run repairs.
Usually. A failing disk is typically imaged (read-only), at least initially, using a hardware imaging tool that has retry features and skips unreadable sectors. The goal of the process is to avoid adding additional stress to the disk. Then, using the image files, the tools will rebuild those images into usable files again. Depending on where the failed sectors exist (one isolated area vs. throughout the disk) some files may still remain unrecoverable.
The cost for recovering one individual drive will start from £300 +VAT once we have completed the free 48-hour initial assessment and issued a written quote. In most cases you only pay if we recover your data. In addition to the drive itself, please send your external hard drive’s enclosure.