What is Time Machine verifying?
I have a 2010 MacBook Pro and always created a backup to a USB-connected hard drive once a week until recently. Earlier this year I set up a WD MyCloud as a local NAS and set this as the destination for my backups. This worked for a while until I got a Time Machine backup verification error, at which stage I had to create a new backup. This takes days over Wi-Fi as my backup is 300GB, but the real issue is that the error reoccurs after some random period. Have you any suggestions, as this essentially means I can’t rely on this method and I’ve reverted to my old one. Brian Walsh
Time Machine verifies things automatically each month. It doesn’t tell you what caused the problem, only that it can’t be fixed and you have to start over. There is an outside chance that it could be caused by a noisy electrical power supply, or a Wi-Fi network operating at the extreme limit of its range, but I’d tend to discount this theory if the problem occurs frequently. By the same token, if it doesn’t happen every month, it can’t be due to your NAS drive not properly supporting Time Machine. In the middle ground of regular but not consistent backup problems, the most likely cause is a hardware fault with the drive itself. I suggest you try another NAS; if the fault disappears, claim on the warranty of that drive.
If you regularly get Time Machine verification errors, check the SMART status of your drive in Disk Utility in case it is failing.