Author: David

TIL I learned how (and how NOT) to restore my Mac backup

They say you never know if you have a real backup until you try to use it. They’re right.

TL;DR

  • Don’t encrypt your drive until you’ve restored your data
  • Don’t exclude things from Time Machine backup

The details

I sent my 2017 MacBook Pro to Apple because the keyboard was acting up. And as long as I was at the Genius Bar, I thought it’d be a good time to mention a weird problem I’d had when using Screen Mirroring on my Apple TV (moving the cursor would reveal things lower in z-order – it was weird); the Genius duly wrote that down and sent my machine to the depot for repair.

A few days later, the machine was back in my hands; not only had they replaced the keyboard and the top case (as I’d expected), but they also had replaced a few other parts – and they’d either wiped or replaced the SSD, so I had a virgin installation of Mac OS and none of my data. I booted up the machine, and, for security, told it to turn on FileVault to encrypt the SSD; then I set about restoring my data.

Plan A

I had multiple backups: Time Machine, a bootable clone drive (made with SuperDuper!), and Backblaze for offsite backup. I thought that the easiest solution would be to reboot from the clone drive and restore to the SSD, so I did exactly that.

The restore went fine, except for one small problem – SuperDuper! was unable to update the PreBoot environment. When I tried to boot from the SSD, I got a blinking folder with a question mark, which meant that the system couldn’t find the startup disk. I booted from the clone again and used System Preferences to set the startup disk to the SSD; this time, instead of the question mark, I was asked for a disk password…which, of course, I didn’t have.

Back to the clone, where I could easily mount the SSD and see its contents. Searching gave me this thread, but I couldn’t figure out how to apply the hints to my environment, so it was time for Plan B.

Plan B

I booted the “Install High Sierra” USB stick I’d kept around from last year and erased the SSD. Then I restored from my Time Machine backup. Many hours later, I was able to boot the SSD, and all seemed well.

Except…my desktop background was wrong. And my Dropbox folder was empty (though that was easy to fix by firing up Dropbox). And when I looked further, I realized that I didn’t have any of my photos, nor my iTunes library, nor my DevonThink databases. It was as if they’d never existed. But they were on the clone drive. Hmmm….

Plan C

I booted the clone and fired up SuperDuper! again. And, again, I restored the SSD from the clone, using “Smart Copy”, which found 150GB already on the SSD, and about 200GB of data that needed to be copied.

This time, when I booted the SSD, all was well – I had all of my data.

I opened Time Machine Preferences and discovered that I’d excluded my iTunes library, my Pictures folder, and my DevonThink databases from being backed up in order to save space on the drive in the Time Capsule that I was sharing among several computers. Oops. Especially since I’d stopped sharing a Time Capsule months ago and was backing up to a directly-attached 4TB drive, with plenty of space.

Conclusion

All seems to be well; I’ve removed the exclusions from Time Machine and it’s busily backing up everything now.

I haven’t checked to see if the Apple TV screen mirroring problem has been fixed – I guess I should find out, though.

I think I’ll wait a few days after Mojave ships before I upgrade; I really don’t want to go through this again any time soon!

TIL how to build Python 3.7 with statically-linked libssl and libcrypto

I use a Virtual Private Server on DreamHost to run the Toastmasters District 101 website. For the most part, I’m happy with their service, and with a shell prompt, it’s usually easy to install whatever software I need.

Except Python 3.7. Python 3.7 requires a newer level of OpenSSL than DreamHost offers, and since I don’t have root access on a VPS, I can’t just replace OpenSSL. Compiling a current version and installing it in a directory ($HOME/usr/local) was easy enough:

./config --prefix=$HOME/usr/local --openssldir=$HOME/usr/local/openssl   
make   
make test   
make install

Building Python 3.7 was also easy, but getting it to use my copy of OpenSSL was not.

At first, I tried adding my OpenSSL to LD_LIBRARY_PATH, which worked, but it made git complain: no version information available (required by ssh), and that seemed unfortunate (and made me worry that I might break other things).

After much searching, I found Python issue 21541, which had the hints I needed to statically-link my copy of OpenSSL into the Python executable.

First, run configure:

./configure --prefix=$HOME/opt/python-3.7.0 --with-openssl=$HOME/usr/local/

Then uncomment and change the section of Modules/Setup dealing with SSL to this:

# Socket module helper for SSL support; you must comment out the other
# socket line above, and possibly edit the SSL variable:
SSL=$HOME/usr/local
_ssl _ssl.c \
    DUSE_SSL -I$(SSL)/include -I$(SSL)/include/openssl \
    L$(SSL)/lib -Wl,-Bsymbolic $(SSL)/lib/libssl.a $(SSL)/lib/libcrypto.a

After that, the usual make && make install worked.