US Patent 10303561 Point-in-time copy restore

Managing storage volumes in a point-in-time copy cascade. The cascade includes a first source volume, a first target volume and a second target volume. The method detects a corruption of the first source volume and, if a first restoration of the first source volume from the first target volume is in progress, creates a third target volume from the second target volume and directs I/O operations for the first source volume to the third target volume. The first source volume is then restored from the third target volume.