Having trouble completing the Volume Structures test on 2 USB 4TB drive (WD My Book) used for TimeMachine. I can successfully launch the Volume Structures test, make sure it unmounted and started testing the drive, and walk away to do something else, but when I return, TTP is no longer running, and there is no report logged in TTP. Volume is left unmounted. Second attempt to launch Volume Structures test complains that the file system is unknown on the drive.

Used Disk Utils to remount and use FirstAid on the drive works fine, seems to be a similar test of the volume structures?

This has happened about 4 times since upgrading to TTP 10.0.1, with no successes.

System: Mac Mini (Late 2012), MacOS High Sierra 10.13.6, 16GB RAM, 2.5 Ghz dual core i5, 1 TB SSD main drive, 2TB SSD secondary drive, 2 x USB 4TB WD My Book external drives used for Time Machine.

In addition to using the 2 USB 4TB drives for Time Machine locally, these are also shared drives for 3 family laptops also using them for time machine. At the time of running the tests, I had turned off both TM and File Sharing.

I use TTP Volume Structures to validate CheckMate reports of a Volume Structures failure (CheckMate 1.1.8 ) which has for a long time had problems with unmounting external drives used for TimeMachine and File sharing, and thus reporting false failures of that test.

This configuration has worked fine with earlier versions of TTP and MacOS for many years, so hoping you are able to identify a bug and produce a fix.

Thanks for your clear and detailed report.

Checkmate is now at version 1.1.8.

Please send a message to This email address is being protected from spambots. You need JavaScript enabled to view it. , including a link to this thread. You will receive a reply by email on Tuesday, and may be asked to send in some additional information, such as an Apple system information report. You may also be given some instructions for looking for log files, which in recent versions of the system software are not as straightforward as they once were. You could try launching the Console application, located in /Applications/Utilities, and seeing if the system.log file mentions the crash. There may also be a crash report in User Reports. The screen capture below shows a report in User Reports of a TechTool Pro crash on my iMac (mid-2010) running macOS 10.12.6 Sierra.

You may also be asked to test one or more beta builds of the program.

In the meantime, please check the WD My Book with the Surface Scan, to check for unremapped bad memory blocks. Thank you.

Just run it again to confirm that I can reproduce the issue, but I can't. It passed this time.

I will follow up as suggested.

Thanks for the update and your cooperation.

Problems that arise on some runs of a program and not on others are particularly challenging to fix, but logs may offer a good hint about the cause of the crash, which might suggest to the programmer a way to reproduce the problem.