Synchronize. Backup. Bootable Backup.
Whatever your backup or sync scenario, ChronoSync has got you covered!
Back to more tech notes


TNCS-0038 - Upgrading to High Sierra

September 27, 2017


It’s that time of year again… upgrade season!

Apple has just released macOS 10.13 aka High Sierra and the rush is on to live on the bleeding edge! As with any major OS update, there are a lot of questions and anxiety floating around. This tech-note serves as a quick guide of things you should be aware of before, during and after you upgrade.

First and foremost, backup your data before upgrading! This should be standard procedure before any update, let alone a major OS release. Why? Because it is distinctly possible that your updated system will fail to boot, perform poorly or even lose data once the install is applied. Admittedly, this possibility is extremely small - probably well under a 1% chance. But do you really want to take that chance?

If you’re reading this, you’re probably using ChronoSync to perform your backups. We’ll assume that you are and that you are making bootable backups. If you aren’t making a bootable backup, stop right now and head over to Standard Bootable Backup. Making a bootable backup is even easier in ChronoSync v4.8 by using an Assistant!

Prior to downloading the High Sierra installer you should open ChronoSync and manually run all non-bootable backup tasks that you’ve setup. This ensures that you have redundant backups of your current data. If you have any scheduled tasks, you should then disable the scheduler by choosing “Suspend Scheduler” from the ChronoSync system menu (at the upper right of your menubar).

When that is all done, run your bootable backup task and test that your backup works. The preferred method is to open System Preferences, choose Startup Disk, and select your bootable backup drive. Restart your system and boot all the way to Finder. If you get this far, all is well. Then open System Preferences -> Startup Disk and re-select your main system drive. Reboot back into it. Disconnect your bootable backup drive. Now you’re ready for High Sierra!

Downloading and installing High Sierra is fairly easy and straightforward. You should expect the process to take an hour or so. Some systems will be faster, some will be slower. When finished, you’ll boot up your new OS, configure your account and iCloud settings and be on your merry way. In the vast majority of cases, that’s it! You’ll be able to use your new OS just as before as if nothing ever happened. Here’s a few things to be aware of, however.

If your system has an SSD as its primary drive, it will be converted to APFS, which is Apple’s next generation file system. The conversion is mandatory - there is no way around it. If your system is a spinning hard disk or Fusion Drive, the conversion will not take place and you will still be using HFS, Apple’s old-generation file system. What’s this mean for you and, specifically, your use of ChronoSync? Well, pretty much nothing. If you simply put your “ignorance blinders” on and not pay attention to the fact that your filesystem may have been changed, everything will be just fine. ChronoSync v4.8.1 works with APFS or HFS. The underlaying filesystem does not affect how you run your backups - even bootable backups!

If you followed our directions, we told you to suspend your scheduled tasks before upgrading your OS. The reason for this was so your backup tasks won't start firing off after you began using High Sierra. The reason for that is so you can take the time to verify that your new operating system is working correctly and that your data is intact before you start running backups. Start with your data files - peruse them in Finder and open a few documents/projects that you regularly use. This will allow you to test your applications, too. Once that looks good, you can resume your regularly scheduled backup tasks by choosing “Resume Scheduler” from the ChronoSync system menu. If you’ve scheduled a bootable backup, however, you should temporarily disable it first by unchecking/disabling it in the Scheduled Tasks Manager window.

You should hold off on resuming bootable backups until you at least have several days of intense High Sierra use under your belt. The reason is simple: the bootable backup that you made is your lifeline in case some major problem with the new OS occurs. If you run a bootable backup immediately, you lose that lifeline. Some OS problems may take a while to materialize, so that is why we say you need to use the new OS intensely before you can build confidence in it. Once you’ve achieved confidence, you can resume your bootable backups.

Well, that’s pretty much it! The name of the game is to always proceed cautiously and think about your actions while performing the update. If something goes wrong, don’t panic! If the issue is with the new OS, there are plenty of online communities for you to seek help in. If the problem is with ChronoSync and/or your backup strategy, contact us and we’ll be happy to help.


We’ve covered the basics, above, and the basics are usually good enough for the vast majority of people. However, there’s a few more considerations we’d like to present.

If you have an adequate drive partition available, consider performing the High Sierra upgrade on it before doing so on your main drive. The basic procedure would be to perform a bootable backup to this spare partition, boot into it and then install High Sierra. This allows you to try out High Sierra on a completely separate device. If all goes well and you are happy with it, you can then perform a bootable backup from that secondary device back to your primary drive.

If you’ve been using your Mac for a while, and have undergone several OS upgrades, there’s no doubt that you’ve collected a fair amount of “cruft” over the years. A clean install is the best way to get rid of that and ensure maximum performance from your computer. You can do this one of two ways. The first is a variation of the above - if you have a spare partition, erase it and run the High Sierra installer. You can then tell the installer to install onto the spare partition.

The second way to achieve a clean install is to boot from your bootable backup and then erase your primary system drive. Then when you run the High Sierra installer, you should select your newly erased primary drive as your destination. You should probably not use this approach if you do not have redundant backup copies of your data. That’s because, for a brief period at least, your bootable backup will be the only copy of your data!

In either case, the new OS will be placed cleanly on the destination device and it will be in as pristine a state as possible. You can use Migration Assistant, as discussed here, to import all your data from your old Bootable Backup.

Note: An external drive may be considerably slower than an internal one. Keep this in mind when making a decision about where to install your OS update.

We mentioned Apple’s next generation file system above and how your primary SSD will be automatically converted to it. You may also manually convert other SSDs and hard drives to APFS using Disk Utility. However, our experiences with APFS has shown that there is little compelling reason to do this - yet! While APFS is cutting edge and a step forward, it is still a bit pokey when compared to HFS. This is to be expected. After all, Apple has had decades to optimize HFS support whereas APFS is just now coming on the scene. APFS may eventually become the performance king but for now, applications that hit the filesystem hard (like ChronoSync) are going be noticeably slower.

If your SSD was forcibly converted to APFS, and you are noticing performance degradation, you can use ChronoSync to revert your built in drive to HFS. The procedure is a variation of Upgrade on Another Partition and Install High Sierra Clean, above. If you have a bootable backup of your High Sierra system, you can boot from it, reformat your SSD as an HFS volume, then run a bootable backup back to your primary SSD. The warning about backup redundancy applies here, as well. You should only consider this if you notice a performance degradation and absolutely need to restore your previous levels. There are definitely benefits to using APFS and, as mentioned above, APFS performance will only get better with time.


If you have any concerns or issues related to High Sierra, please do not hesitate to contact us.


Sept-27-2017 - Created.