Running memtest86 on a Mac Mini

At $DAYJOB, we are having issues with a Mac Mini that is acting up. It crashed on boot, and re-installing macOS didn’t help as it complained about the file system being damaged, no matter if I reformat (“erased” in Apple-speak) or repartition the disk. The built-in Apple Diagnostics tool crashed after about 16 minutes, so I thought I’d run memtest86+ on the machine. But without a working OS boot, I was unable to get it up and running, and googling for information didn’t help.

To get it running, I had to create a bootable USB stick, for which I had to find a Windows machine and run their USB Key installer. However, the disk did not show up in the list of boot options when booting the Mac Mini pressing the Option key. To find it, I had to install rEFInd on a second USB stick (they have a USB flash image ready for download, so no Windows machine needed).

With both USB sticks in the Mac, booting with the Option key let me select the rEFInd USB stick, which in turn found the memtest86+ stick as a “Legacy Windows” image. Now the test started fine.

The futility of OSX parental control and web browsers

I have kids. Two of them, the youngest is five and the oldest is about to turn eight years old. Since they see me and my wife use a computer regularly, they of course also want to use it. The oldest has access to computers at school, and if they are going to be proficient with computers, they need to start using them at an early age. I have a MacBook Pro that they both have accounts on, both set up with OSX’s default “Parental Control” feature.

That works fairly well when they use the local application (Photo Booth is a favourite, if I hadn’t blocked it their little clips would probably have ended up on YouTube if the knew how to upload them). Well, before getting to the applications, there are all these little pesky pieces of software that phone home on every start-up, under the guise of doing software updates. No matter how many times I block “Google Software Update” or “Paragon Updater” and the like, every time they log in to their accounts, they get a message that they cannot run them. Well, they learn to click “OK” and go on with their life. Using a web browser is a lot more hassle, though.

I had initially set up a whilelist in the Parental Control settings, to only allow them to access certain web sites. That doesn’t work, since every site in the universe now include stuff from other places, either be it CDNs, Google’s web tracking stuff or a JavaScript library that they are too bored to copy to their own domain. I can live with that, a lot of it can be blocked with Ghostery or similar, but that is if you can even get to it.

Trying to even run a web browser on an account that has Parental Control enabled is a chapter in itself. First it is the phone-home auto-update stuff that kicks in every few moments. Then there are the pre-installed shortcuts (at least in Opera) that wants to download screenshots to display inside the Speed Dial screen (why can’t they just ship with default images?). Then even trying to type a web address keeps trying to send every single keystroke to Google, requiring having to close a dialog after every single letter in the URL. In Google Chrome, it seems utterly and completely impossible to disable this behavior. Opera has it, hidden deep inside its configuration options, but I then I have to enter a magic key combination to remove the Search field. And fight the blocked URL pop-ups to remove the pre-installed Speed Dials.

I need to try out Vivaldi for the kids’ accounts. I know it can be configured to be less intrusive, and it doesn’t send all keystrokes to the search engine. When I set up the account for my oldest daughter there wasn’t a stable version around, but it should be fine now.

OS X Time Machine recovery does not find my USB disk

Today the root file system on my MacBook developed an “Invalid index key” error that I was unable to fix by booting into recovery mode and using the Disk Utility, or even by booting into single-user mode and using the fsck_hfs tool, no matter what flags I threw at it. Paragon HFS for Windows could still read (and write) to the partition from the Windows installation and I was able to read the file system, but I couldn’t boot it.

After a few hours of trying to fix the problem, I simply gave up. I saw several mentions of a tool called Disk Warrior that supposedly could fix a lot of the problems fsck couldn’t, but I was a bit reluctant at throwing over 100 US dollars at a tool that I didn’t know if it would make any difference.

I do have backups. Even if the MacBook isn’t set up to do daily backups like most my machines are (I never got the Time Machine interface in my Synology NAS to work with it), so the last backup I had was from December last year. Better than nothing, and I don’t really keep that many important files on the laptop – most of the important files are shared with other computers (using Git version control to synchronize), or in Dropbox.

So I booted from the recovery partition, selected Restore from Time Machine and … my backup didn’t appear.

So I rebooted. Still nothing.

Rebooting, this time booting from the backup disk (which has a convenient OS image installed onto it). Still no disk. I only saw my (failed) attempt of a backup node from the Synology NAS get listed (and I was unable to connect to it, just like Time Machine itself was).


Then it struck me. What if I power off the Synology, and then open the recovery program? So that is what I tried, and there it was! Now the recovery finally let me select the disk that was physically connected to the machine, rather than the network share over WiFi (still, it’s quite impressive of it to find it when booting from the recovery partition on the backup disk, I must say that Apple are rather good at making those things just work, even if it failed at what I really wanted to do).

Now the backup is finally restoring. The clock is approaching half past midnight and it is at 7.5 % restored, so I guess I will have to wait until the morning until I see if it actually did work, but at least it is trying now…

Time to go to sleep.