The Fatal Flaw of Time Machine and Data Recovery from a Seagate Expansion Portable Drive

Let’s face it. Time Machine is great. Plug in an external hard disk. Click on a button, and when the process is done, you have a complete backup of your iMac or MacBook. (In fact, in some cases, this process will be totally automatic – without any user intervention). You’ll be hard pressed to find a backup solution that is so seamless. So, what could possibly go wrong?

Well, last week we came across an interesting case. A user decided to perform a fresh installation of MacOS on his iMac. The operating system on it was running rather slowly. So, using Time Machine (software) in conjunction with an external hard drive, he performed a complete backup of his system. He then proceeded to wipe his internal disk, safe in the knowledge that he had a complete, up-to-date backup stored on his external drive (a Seagate Expansion Portable 2TB).  

On the wiped internal disk, he re-installed MacOS Catalina. In less than 90 minutes, he had a nice and fresh operating system (Catalina 10.15.7) up and running. All he had to do now was to import his old applications and data which were safely backed up (or so he thought). He connected his Seagate Expansion Portable disk via USB and opened Migration Assistant. To his horror, though, no disk was detected. He checked the USB and power connections. They appeared to be okay. He disconnected and reconnected the disk, but no disk showed up.

When a Time Machine backup disk won’t restore…

He phoned Apple technical support. They advised him to start his iMac in Recovery Mode. From there, the option to restore from Time Machine was also presented. In Recovery Mode, he selected this option and his disk was finally recognised. But the about three quarters of an hour into the data migration process, he was greeted with an error message indicating that the migration process “could not complete”.

On his second call to Apple technical support, they suggested to him that he contact a data recovery service!

The fatal flaw with Time Machine

While Time Machine processes such as Fsevents and Spotlight are very clever in backing up files incrementally, TM does not appear to check the condition of the target disk. Coupled to this, MacOS’s Data Migration process is uber-fussy about disk condition. Any hint of a disk problem and the migration process can come to a shuddering halt. So, while MacOS will allow you to back up to a disk which is going bad, it won’t let you restore from one.

Recovery from Time Machine disk

For our customer, we made the process as stress-free and economically as possible. His Seagate Expansion disk had over 47,000 bad sectors and some translator (firmware) issues which were making some disk sectors invisible. While some of his application, files were damaged, we managed to retrieve most of his data files intact.

Solution to the Time Machine Problem

Apple badly needs to incorporate some kind of disk health-check utility into Time Machine. This could save a lot of users the stress and hassle of data loss situations.

In terms of what the user can do to prevent this sort of event, don’t just rely on one backup disk. Use two. Moreover, you can mitigate the risk again by using third-party backup software on your Mac such as Carbon Copy Cloner or Super Duper.

Having problems restoring a Time Machine backup? Drive Rescue offer a complete external hard disk data recovery service for external Seagate Expansion Portable disks. Phone us on 1890 571 571