Verification of computer backup data

A method of backing up source data from a source storage volume of a source computer over a network to backup media controlled by a backup server on said network, comprising:

• storing the source data on said backup media as backup data with an associated hash of said source data generated by said source computer as the source data is read from the source volume for storing on the backup media, the backup data and the hash being associated with one another on the backup media;
• reading by the backup server the backup data and its associated hash from the backup media;
• generating by the backup server another hash from the backup data read from the backup media;
• comparing by the backup server the associated hash read from the backup media with said other hash generated by the backup server to verify the integrity of the backup data;
• and upon said compared hashes not matching, marking the backup data as miscomparing to indicate that the source data is to be rewritten from the source volume to the backup media.

Computer readable media comprising instructions executed by a source computer and a backup server of a computer network to perform a backup method to backup source data stored on a source storage volume of said network, the method comprising:

• reading by said source computer at least a portion of source data from the source storage volume;
• generating by the source computer a hash of the source data as the source data is read from the source volume;
• transmitting by the source computer the source data and the hash to said backup server;
• writing by the backup server the source data and the hash to backup media;
• associating the hash on the backup media with the backup data corresponding to the source data from which the hash was generated;
• reading by the backup server the backup data and the hash from the backup media;
• generating by the backup server another hash from the backup data read from the backup media;
• comparing by the backup server the hash read from the backup media with the other hash generated by the backup server to verify the integrity of the backup data;
• and upon said compared hashes not matching, marking the backup data as not comparing to indicate that the source data corresponding to the backup data is to be rewritten to the backup media upon performing a subsequent backup.