Recovering from Error 206, Media Failure
Retrospect reports error -206, media failure, when it is unable to properly read or write data to your backup set. In most cases this error indicates that the backup media has a failed or contains a damaged block, so that the backup device simply cannot read a portion of your data. Error -206 is reported to you via a dialog and an entry in Retrospect’s operations log. This technical note helps you determine what to do after you receive an error -206. The -206 error is a hardware error reported by the storage device.
If you encounter error -206 while backing up, the first thing to do depends upon your backup set type:
Backing up Tape
If you are using a tape drive, you should immediately use your tape drive head cleaner, per the tape drive vendors recommendations. If you don’t own a tape drive head cleaner, this could be the root problem: most tape drives require regular cleaning of the heads. Check your tape drive vendors documentation for recommendations.
After cleaning the tape drive heads, if appropriate, try your backup operation again using a different tape. If no further media failure errors occur with other media, you likely just had a bad tape. Label the first tape as possibly suspect, and set it aside.
Tape drives sometimes report media failure if you try to append to a tape that previously was being written to when you experienced a crash or power failure. If you know you are in this case, you may tell Retrospect to continue your backups to a new tape (Go to Configure>Backup Sets, configure the set, then go to the Options tab and tell Retrospect to skip to a new piece of media), you may retire the backup set (that is, stop trying to append to it, and just start a new set with different media), or you may recycle the backup set, re-using the tape. Erasing a tape clears the error state of the tape caused by the previous crash or power failure. To avoid this problem in the future, be sure to let tapes rewind completely before powering off the tape drive and computer, and rewind and eject tapes manually before rebooting if your computer crashes during a backup.
Backing up Disks/Removable Media
Try a different piece of media. Usually error -206 with a removable storage device such as RDX drive could indicate that a specific disk has a failure. If the error does not occur with other media, label the original media as suspect, and set it aside. While you may be able to re-use it after reformatting it, we don’t recommend this. Since the point of backup is preserving your data, it doesn’t make sense to take risks with media that may be substandard.
If the error happens with multiple disks, then it could point to a communication problem with the RDX storage device. Try a different USB cable or even a different USB port connecting the device to the computer. Consider trying the backup device on another machine to see if the problem follows the device.
File or Disk Backup Sets
If you are backing up to a hard disk or file server (NAS Device), an error -206 may indicate a failure on the backup set media or a communication failure with the device. For example, if you are backing up to a networked disk or file server, and there is a network connection failure, Retrospect may report error -206. Verify that the network connection is not failing, and re-try the operation. Restart the NAS hardware if needed. Try a new network cable for the backup server and the NAS device. If errors persist, there may literally be bad media on the volume you are backing up to. Try backing up to a different volume, and check the original volume for errors using a disk checking utility. If you are backing up to FireWire/USB hard disk, an error -206 can occur if the device is unplugged during reading or writing. Verify that no connections are loose, and re-try the operation. Try a different device cable or even a different device port connecting the device to the computer.
If you are backing up to a Cloud backup set and encounter an error -206, you likely are actually experiencing a network communication failure. You may simply have lost your connection. Verify that the network is working properly, and re-try the operation.
Media failure messages during a restore usually indicate an actual failure of the media on a specific tape. Follow these steps to troubleshoot:
Clean the heads on the tape drive. If you don’t own a tape drive head cleaner, this could be the root problem: most tape drives require regular cleaning of the heads. Check your tape drive vendors documentation for recommendations. After cleaning the heads, re-try the restore. If it succeeds, you are lucky. Set up a regular schedule for cleaning the heads on your tape drive, to avoid future trouble.
Try restoring the data from a different backup set. If you are not regularly backing up to at least two backup sets, you should for maximum data protection.
If you cannot retrieve the data from a different backup set, simply try the restore again. Does it fail in exactly the same place? If not, the failure may be caused by interference with other electronic devices. We have seen media failure errors caused by vibration, proximity to large video monitors, proximity to electrical conduits running behind walls, huge magnets, as well as computer peripherals. If your media failure errors are not consistent, try isolating the backup device, to see if the error is caused by device interference. Isolating the device may be as simple as moving it a few feet away from your video monitor, or if it is on a chain of SCSI, USB, or IEEE 1394/FireWire devices, removing the other devices so that your tape drive is alone on the bus. If your device is external, you may also try using it on a different computer, if you have one available.
With some tape drives you will be able to recover data from later portions of the tape beyond the damaged spot. Many tape drives, however, will not proceed past a media failure. In some cases you can get a drive to move past a media failure by starting a retrieve after the point of failure. In other words, if you can determine the backup session date and time that contains the failure (by looking at the error Browser, or by looking at the file name Retrospect was trying to restore when the failure occurred), you may be able to restore files later in the set, by starting a restore with the next or another later backup session.
If you have another compatible backup device, it is worth trying to retrieve the files there as a last resort, as different devices will sometimes react to media damage in different ways. If the compatible device is on another computer, copy the backup set catalog over to the other computer, and try the restore there. If this works, your original drive may be failing. Contact your drive vendor for further assistance.
If the media failure message persists with multiple tapes, and you have eliminated the above possibilities, you may have a failing backup device. Contact your drive vendor for further assistance.
Restoring Disks/Removable Media
Try restoring the data from a different backup set. If you are not regularly backing up to at least two backup sets, you should.
If you cannot retrieve the data from a different backup set, you should be able to recover data before and after the failed spot on your disk.
You may also try restoring the data in a different drive, if you have access to another drive that can read your media. Sometimes different drives are able to read data on marginally damaged or failing media.
Restoring File or Disk Backup Sets
Try restoring the data from a different backup set. If you are not regularly backing up to at least two backup sets, you should. Refer to the Hints section below for tips for future reference on avoiding media failure problems in the future.
If you cannot retrieve the data from a different backup set, you should be able to recover data before and after the failed spot in the file set.
Perform a Tools>Verify operation on the set. If the error is reported in the same location (view Retrospect’s operations log for details), then likely the disk storing the file backup set has a bad block in that location. If the error is reported differently each time, it may be a communication problem. If your file set is located on a file server, there may be network communication problems. Verify that the network is functioning properly. If your file set is located on an IEEE 1394/FireWire/USB hard disk, verify that there are no loose connections, and re-try the operation.
Hints for the future
The best way to protect yourself against data loss is to regularly back up to multiple rotating sets using verification for all backups. Refer to the Retrospect User’s guide for complete backup strategy and media handling and storage recommendations. Some key points to remember are:
Back up to multiple sets.
Always back up using verification.
Regularly rotate new media into your backups.
If using a tape drive, regularly clean the heads per the drive vendors recommendations.
Keep computing environment clean of dust, smoke, and moisture.
Keep backup media stored in protective cases or covers when not in use.
Regularly store backups off-site.
In a network backup situation, don’t forget to back up your backup computer.
Periodically use Retrospect’s Tools > Verify option on a backup set to verify that all is functioning properly.
Last Update: August 1, 2016