SQL Backup Recovery error-the media set has two media clusters, but only one

Error description:

During the SQL database backup and restoration process, "the media set has two media clusters, but only one error is provided" (as shown in ).

Figure 1. Error

Cause of error:Multiple devices are selected during the backup process, and data is backed up to these devices in segments. This error is caused by only one (or more) device in the restoration process. We may mistakenly assume that the selected device is the backup target. In fact, all the devices that appear in the backup list are the target device. In this way, all the backup media clusters must be selected for restoration to meet the requirements.

Figure 2. Back up data to multiple media Clusters

Figure 3. Restore from multiple media Clusters

The following is an introduction to sqlserver help.

Serial number

The correct sequence is important for multiple backup media in multiple media clusters or media clusters in a media set. Therefore, the serial number is assigned as follows:

• Ordered media clusters in a media set
  In a media set, the media cluster is numbered in sequence based on the position of the media cluster in the media set. The media cluster number is recorded inBackupmediafamilyTableFamily_sequence_numberColumn.
• Physical media in a media Cluster
  The Media Serial number indicates the sequence of physical media in the media cluster. For the first backup media, the serial number is 1. The first backup media is marked as 1, the second media (the first continuation tape) is marked as 2, and so on. When restoring a backup set, the Media Serial Number ensures that the operator responsible for restoring the backup loads the media in the correct order.

Precautions for using multiple devices

When you use multiple tape drives or disk files, note the following:

• Considerations during Backup:
  The entire media set created by the backup operation must be used for all subsequent backup operations. For example, if a media set is created using two tape backup devices, all subsequent backup operations involving the same media set must use two backup devices.
• Notes for restoration:
  All media clusters must be mounted at the same time for restoration from disk backup and any online restoration. For offline restoration from tape backup, you can process a media cluster on a backup device with a smaller number of media clusters. You must complete processing of each media cluster before you can start to process another media cluster. Media clusters are always processed in parallel unless a single device is used to restore a media cluster.