I save my photos, music and videos on disk as well as external hard drive as a second back up. I'd used Verbatim and Maxell disks previously and suffered minimal loss which was acceptable and easily replaced. I saw these Sony disks for, at the time, a slightly cheaper price so went ahead and purchased a stack. I continued to back up data on the remaining Maxell disks I had interdispersed with the Sony disks using the same computer. All the disks are stored together.
Just over a year later, having had a recent hard drive crash I needed to upload many Gb of data. The Maxell and Verbatim disks loaded and were copied 98%. Unfortuantely many of the Sony disks are no longer readable and others can be only be viewed and played but not copied which is not very reassuring if they were the only copies left. I'm having to check every Sony disk and constantly getting the same disappionting result. Maybe I got a bad batch. Bit late now.