Author Archives: Raoul Pop

How To

To split or not to split your Mac’s Fusion Drive

In a recent post, I wrote about upgrading the original (failing) blade SSD in my iMac to a bigger and faster NVMe module. During that upgrade process, I wondered whether splitting my Mac’s Fusion Drive would result in better performance, but decided against it for simplicity’s sake.

Even though I decided against splitting my Fusion Drive at that time, I read articles that advocated for it and suggested even better performance was to be had by allowing the SSD and HDD to run as separate volumes. The idea is to install the OS and select files and folders on the SSD, with the bulk of the files on the HDD. For the sake of experimentation and learning something new, I decided to tinker with my iMac and see if I could squeeze out some extra speed.

For those who are wondering what I’m talking about, Fusion Drive is an Apple technology built into macOS that creates what is essentially a hybrid drive, by combining an SSD module (NAND flash) with a traditional HDD (platter drive) and presenting the two as a single volume to the user. The protocols that govern the data I/O are called Core Storage. Apple writes: “Presented as a single volume on your Mac, Fusion Drive automatically and dynamically moves frequently used files to flash storage for quicker access, while infrequently used items move to the high-capacity hard disk. As a result, you enjoy shorter startup times and — as the system learns how you work — faster application launches and quicker file access.”

I’ve been using Fusion Drive since it came out, retrofitting my iMac at the time with a new blade SSD and thus making it run faster than its original specs. I love this technology, because it offers significant performance improvements for a fraction of the cost of buying a large SSD, which used to be be quite expensive a few years ago.

The long and the short of it is that it’s not worth it to split your Mac’s Fusion Drive. If you’re currently running Fusion Drive on your Mac, keep doing that, you won’t see any significant performance improvements if you split it. Actually, some things may run slower than before, and you’ll also have to deal with a few inconveniences, as detailed below.

I’ll present both scenarios here and you can decide what to do for yourself. There are multiple methods to it. These are the methods I’ve chosen. The number of Terminal commands that you have to run for either scenario is minimal, and the time involved has to do mostly with backing up your computer, waiting for the OS to reinstall and for your data to be restored from backup. For example, if you’ve got a 3TB drive and you’re at about 50-60% usage (and you should be at that threshold or lower on any hard drive), then you should figure on 4-5 hours for either of the two scenarios.

How to split your Fusion Drive

First and foremost, did you backup your computer? If you did, go ahead and create a bootable drive using Apple’s instructions, then boot into it by pressing the Option key as soon as your Mac restarts and holding it down until you see the Apple logo. You need to boot into a separate drive because you’ll be deleting your internal drives entirely, including the boot and recovery partitions.

Once you’re in, open Terminal and get a listing of your disks and volumes.

diskutil list

Your Fusion Drive presents itself as a logical volume group that appears as a separate disk with an HFS+ or APFS partition. Say your SSD is disk0 and your HDD is disk1, your Fusion Drive would be disk2 or disk3. In my case, it was disk3 (disk2 being the bootable recovery drive). Now unmount your internal disks.

diskutil unmountDisk disk0

diskutil unmountDisk disk1

You’ll want to delete that entire disk containing Fusion Drive. Be forewarned, this deletes all you data. Did you backup your computer?

diskutil apfs deleteContainer disk3

Now that Fusion Drive has been nuked, you’ll still have your separate drives that you’ll want to make sure are erased. The eraseDisk command requires that you offer a new name for each disk, so I chose to name them SSD and HDD, to keep things simple.

diskutil eraseDisk JHFS+ SSD disk0

diskutil eraseDisk JHFS+ HDD disk1

Now you’ll want to do a fresh install of macOS onto the SSD, and after that’s complete, you’ll boot up into your fresh install and go to Utilities/Migration Assistant, in order to do a selective data restore. Here you’ll have to decide for yourself, based on the total size of your SSD and your data set, how much of it you’ll want to restore onto the SSD. The rest you’ll need to copy manually from the backup drive onto the HDD. In my case, I restored my user settings and the system and libraries folders onto the SSD, and I copied the following folders onto the HDD: Documents, Downloads, Movies, Music, Parallels (in case you’re running some kind of VM software) and Pictures. Each of those folders was too big to keep on the SSD, even though I have a 512GB module (remember the rule about keeping your drive at or below 50-60% usage).

Once you complete all that work, you’ll need to create links to these folders on the HDD in place of your folders on the SSD. Mojave won’t let you do this when you’re logged into your account, so you’ll need to boot up into recovery mode and open Terminal once more.

Go to your homefolder on the SSD.

cd /Users/yourusername

Delete the folders that are now present on the HDD. You’ll need to do this for each folder that you’ve moved there. Hopefully you’ve written down their names ahead of time.

sudo rm -rf foldername

In your homefolder on the SSD (same location as above), make links to the folders on the HDD. I chose to put mine at the drive’s root level. You may choose to put them in a folder. Just don’t give it the same name as your username, I hear that may cause problems. You’ll need to do this for each folder.

ln -s /Volumes/HDD/foldername

That’s it, restart and use your computer. However, you may find a few inconveniences — these are the ones I experienced:

  • I noticed no performance improvements. There wasn’t even an improvement in the bootup time. Nothing, nada, zilch.
  • While Apps may open up faster, if they’re still accessing files on the HDD, editing will still be sluggish. In order for you to see that performance boost talked about with SSDs, both apps and their files need to be on the SSD.
  • In my case, I had to keep the Photos library on the HDD, because it was too big to keep on the SSD, and while Photos may have opened up fast, loading up the library took forever, until enough of the recent photos were cached on the SSD to allow me to work with my library. So things were a LOT slower with this app.
  • I kept my mailboxes on the SSD so I was hoping for better performance from Mail, but I didn’t get it. I have a lot of mail stored locally, so in theory, things should have worked faster because everything was on the SSD, but they didn’t. I also experienced odd issues, like when moving messages between mailboxes, it took a lot longer and sometimes didn’t register. I’d drag and drop them, then come back to the app a little while later and find them in the same place, just as if I hadn’t moved them.
  • iCloud would display an odd notification icon, but when I’d go into it, there was no message. This icon was displayed continually for as long as my Fusion Drive was split. See the screenshot below.
  • While Time Machine will backup both internal drives, data restores will only restore the files from the SSD. I don’t know why and I don’t know how to fix that, so keep this limitation in mind. You can go into the Time Machine drive manually and copy the files over afterward, but if you run a restore operation on your computer and you wonder where most of your stuff is after it’s completed, don’t freak out, just know you’ll need to get it manually from the drive.
See that “1” over iCloud? It was there all the time.
This is the kind of performance the SSD provided when my Fusion Drive was split. It looks impressive, but hold on until you see the same test with Fusion Drive enabled, later down in this post.

How to enable your Fusion Drive

After about a week of running my Mac with a split Fusion Drive, I’d had enough and decided to re-enable it. Here’s how I did it. Before you proceed with this, I’ll ask you again, did you do a full backup of your computer? This will wipe all your data.

Using the same bootable drive, I booted into it and opened up Terminal. Since you’ll be wiping all your internal drives again, you need to be booted from an external drive.

Apple recommends this single Terminal command that is supposed to do everything in one fell swoop. It didn’t work for me, perhaps because my SSD module was a newer NVMe running off an adapter card, not the Apple-approved blade SSD manufactured specifically for this kind of thing.

diskutil resetFusion

I had to do it with a few more commands. First, find out your disk IDs.

diskutil list

Now unmount your internal disks.

diskutil unmountDisk disk0

diskutil unmountDisk disk1

Then create a merged virtual hard drive with Core Storage.

diskutil coreStorage create Macintosh\ HD disk0 disk1

Now get its logical volume group name (the very long alphanumerical name that appears in Terminal after you type this command).

diskutil coreStorage list

Now format and create the JHFS+ volume that will run Fusion Drive.

diskutil coreStorage createVolume yourlogicalvolumegroupname jhfs+ Macintosh\ HD 100%

Don’t worry about formatting the drive to APFS. That’ll happen automatically when you install Mojave. Besides, APFS is not an entirely separate file system, it’s a container running inside HFS+, so like I said, don’t worry about it. That’s it. Now quit Terminal and do a full restore from Time Machine, but prepare yourself for an incomplete data restore (see the reasons given in the previous section). Once the data restore is complete, you’ll need to manually copy the folders that are missing from the Time Machine drive. Or, as I did, you can do a full restore to a backup set that existed before I split my Fusion Drive, which means you’ll get all your old data back in all the right places, but you’ll still need to get your newer files manually from the Time Machine drive.

In my case, I needed to copy the mailboxes, which are located in ~/Library/Mail/V6 from the newest backup set (the one with the split drive) to my computer, and that gave me all my mail, including the interim stuff. I also copied the latest Photos library, and that gave me all my photos, including the interim stuff. Then I went through the Documents and Downloads folders on the Time Machine drive, sorted by date modified and copied the interim files onto my computer. I didn’t need to go through the other folders because I knew I hadn’t worked on other stuff. And once I did this, my data restore was complete. Mail and Photos still needed to rebuild their libraries though, and that took a while.

And because I use Backblaze to backup my computer offsite, I also needed to uninstall and reinstall that, then inherit a previous backup state (don’t worry about this if you’re not using Backblaze).

When that was done, Backblaze told me it had “made” my computer inherit my backup state, as if it had forced it to do this, in a non-consensual way. Kind of a funny way to word things, but their service works well.

Here’s the kicker. I ran another drive performance test after all this, and these were the results.

Actually a little bit faster than before 🧐

Everything runs fast now, and it runs as expected, without hiccups.

As I said at the start of this article, if you’re already running Fusion Drive, do yourself a favor and leave it running. You’ll avoid headaches you don’t need, unless you like complications.

The only way I can see to speed up my iMac even more, is to purchase a large 3-4TB SSD and run it as my only internal drive. That might be a little faster. But as you can see from the test screenshot shown above, my iMac is no slouch right now. And 4TB SSDs are still fairly expensive. It might actually be cheaper (and possibly faster) to get a 2TB SSD and a 512GB NVMe module, and run them together with Fusion Drive, although the overall capacity wouldn’t be the same. Food for thought.

Updated 7/30/21: I’ve since bought that larger 4TB SSD and I am very happy with the performance. Also, the Fusion Drive protocols will NOT allow you to create a Fusion Drive with two SSDs (or one SSD and one NVMe). They require the use of one SSD and one HDD. So, final(?) conclusion on this matter: larger SSDs are more affordable now and getting a nice, big one and running that alone without bothering with Fusion Drive is a viable and preferred option. Otherwise, stick with Fusion Drive.

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Places

A snowstorm in early autumn

We were driving on the Felbertauern Strasse, a scenic alpine road in Austria known for its beautiful views and its tunnels, when the weather turned foggy and chilly. We stopped for a bit at a place called Rastplatz Elisabethsee to have a look around, and we were treated to these wonderful views of the mountains above, the Osttirol Alps, where a snowstorm had begun, even though it was still early autumn. The contrast between the greenery being covered by fresh snow and fog was so wonderful to see, and it was a reminder of how quickly the weather can turn at high altitudes. Enjoy the photographs!

  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
  • The Alps, Osttirol, Austria
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Apple iMac
How To

An upgrade to my 2013 iMac

I’ve worked on a few upgrades to our family computers in recent months: my 2008 MacBook Pro, my mom’s 2007 iMac and my own late-2013 iMac (A1419, EMC 2639). This is the tale I’d like to recount for you now, because it’s something that I’ve had to deal with since last autumn (october of 2018), and I’ve just recently (I hope) finalized the upgrade/repair. There’s a valuable lesson in here for the people at Apple Support, if they’re interested.

It started with my iMac slowing down to a crawl over the course of a few days, back in late 2018. At first I thought it was spyware or a virus. I checked everything: every app, every file, every process. I removed apps, one by one, to see if it would fix the problem. It didn’t. I ended up removing all of the apps but those that came with macOS, and the problem still persisted. I wiped the drive clean and reinstalled the OS, then reinstalled the apps anew, one by one. It was just as bad. I ran hardware tests using Apple’s software and everything checked out. I scoured the web for solutions. There were some suggestions online that iCloud could cause slowdowns when the syncs weren’t going properly. I checked the Apple Server Status page and indeed they’d been having some problems with iCloud, but they were marked as resolved. I checked Photos and there were major issues: my photos weren’t syncing properly across my devices, and there were image compression/corruption (?) issues going on, with diagonal blue lines appearing all over my recent photos, lines that persisted even when opening the photo at full resolution.

I called Apple Support and began a series of interactions that did not end with any sort of solution. From the start, they agreed that iCloud was causing the slowdowns and had me go through a series of steps such as logging in and out of iCloud, disabling and enabling the various iCloud syncing options, etc. to no avail. Mail started acting up as well, so they suggested I disable Mail syncing, because I had “too many messages in my mailbox”. Documents started acting up, with iCloud Drive showing up empty on my computer, so they suggested disabling that. In spite of the fact that I’d already done it, they tried to convince me to reformat my computer and start fresh. I kept getting a hunch that something else was amiss and asked them if they were sure this wasn’t a hardware issue. They said no. They told me to wait for the photos to finish syncing, then enable the other iCloud features one by one, and things would get back to normal. They didn’t. We kept going back and forth, with Apple Support posting one update per day (or less) to the case, asking me to do this and that, and even though I’d complete their requests and post more updates during the day, they wouldn’t respond till the next. I offered to pay a case fee to expedite issues. I explained to them that this was my main computer and I couldn’t do my work. This went on for weeks, with me getting more desperate and the techs telling me they’d stop helping me because I couldn’t stay calm.

With things going nowhere and Apple Support techs who couldn’t care less, I decided to exercise the “nuclear” option. I found Tim Cook’s email address and wrote him an email. I didn’t expect a response, but I wanted to vent. To my surprise, a short while later I got a response, not from him but from his office, promising me my issue would be forwarded onto someone who would get back to me. I waited a couple of days and… nothing. No one contacted me. I figured I’d try my luck again. I got the same response, but someone finally contacted me and connected me directly with an advanced support technician. There’s apparently a “third tier” of tech support that is only available on a case by case basis; I guess after almost a month of my computer being down for the count, I qualified.

It took a while longer to get to the bottom of the problem: daily communications, screen sharing sessions, uploading log files to Apple servers, trying various steps, etc. It took over a week. iCloud was at first to blame, then Adobe software, then finally, after my case was put in front of a senior technician directly responsible for iCloud connectivity, my issue turned out not be software related at all, but caused by hardware. Hold on to your hat, because as it turns out my HDD was going bad. That was it. It was as prosaic as that! In total, I’d lost over one month of my time and I had to appeal to Tim Cook’s office, all because Apple Technicians couldn’t pinpoint a failing hard drive from the get-go.

Once the problem was found out, it was an easy enough fix. I opened up my iMac and replaced the HDD with a fresh one. I also found and installed a piece of software called DriveDx, which gives detailed stats about hard drives and can let you know of a bad drive before it actually fails. Most drive diagnostic apps rely on the S.M.A.R.T. status flags, but that’s not enough. DriveDx does a whole lot more. The app quickly let me know that the blade SSD (the second half of the Fusion Drive on my iMac) was also close to its lifespan. Since it was still working okay, I decided to hold off on replacing it last year, choosing to monitor it with the app and only replace it when it was close to failing. Here is a gallery of photographs from the time I replaced the HDD. I also chose to take apart the chips and heat sinks and to replace the thermal paste, which had become dry and cracked. Before I put my computer back together, I cleaned the case and the parts thoroughly with a brush and soft cloth, because a lot of dust had accumulated inside and on them. After I put my iMac back together, it worked beautifully once again. I know I could have replaced the HDD with an SSD, and I plan to do it in the future. It’s just that I want to get a 3-4 TB SSD and their prices are still a bit high.

A few weeks ago (about seven months after replacing the HDD), DriveDx told me the blade SSD was fairly close to failing, so I chose to replace it with a Samsung 960 Pro M.2 512 GB NVMe SSD module that I already had, so this upgrade only cost me about $16 for a Sintech NGFF M.2 NVMe SSD Adapter Card, which seems to be the card everyone recommends for MacBooks and iMacs.

I’ve enclosed a separate gallery of photographs of this upgrade below. You’ll laugh when you see one of the photos, so I’ll explain: in what seems to be an iMac design flaw, the cylindrical bracket that secures the screw for the blade SSD is only glued to the motherboard. Unlike every other screw bracket which is secured directly to the motherboard with metal, this one is not designed into the motherboard. Underneath it, on the other side of the motherboard, there are circuits running right across that spot. It seems to me like at the time (2013), the blade SSD and its screw bracket were afterthoughts of sorts for the hardware design team. My bracket came right off the motherboard. I had no glue in the house, only some silicone-based adhesive that takes up to 24 hours to harden, so I put a dab of that under it, tightened the screw and stuck a wood shim in-between the case and the top of the screw, to hold it in place while the adhesive hardened. I know it looks terribly unrefined, but it’s been working fine.

There are two things I should tell you about this upgrade: (1) this particular SSD tends to run hot, so DriveDx will warn you about its temperature, and (2) after booting up my iMac for the first time, it didn’t see the new NVMe SSD, so I powered it down, opened up it up again (thank goodness I hadn’t yet closed it completely) and re-seated the SSD and its adapter in the blade SSD slot. After I did that, it saw it, recognized it, and I was able to boot into recovery, go into Terminal and recreate the Fusion Drive, then reinstall the OS and restore my data.

In spite of the temperature warnings, my iMac has been working great so far. I noticed a bit of a speed boost, but since I’m still using Fusion Drive and I’m tied to a spinning hard drive, a lot of the oomph of the SSD can’t be seen. I suppose I could have chosen to install the OS on the SSD and keep my files on the HDD, but I prefer to work without complications. A single 3.5TB volume works for me. If I could have a single 24TB drive that holds my OS and all my files (that are currently sitting on three external hard drives), I’d be happy with that.

I would like to thank Tim Cook’s office for responding to my messages and getting me out of a real bind. I was at the end of my wits at the time, so the tone of my emails to them was gruff and biting; they could have chosen to ignore me. I don’t know what I’d have done if they hadn’t stepped in. But I do wish I didn’t have to exercise that option. Apple Support should have found out the issue from the start. It wasn’t something arcane, it was a simple drive failure.

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A 1970s Tressa Automatic Watch
My Watch Collection

A 1970s Tressa Automatic Watch

This is a 1970s Tressa Automatic wristwatch with an Incabloc 25 jewel movement and date function, serial number 81272. I purchased it in the autumn of 2016 and had it fully serviced by my watchmaker. This watch keeps incredibly accurate time and is very sturdy, in spite of its currently low market price. It has about a 2-day power reserve. The date can also be adjusted separately from the time, once again pretty surprising for a watch of its price. The elastic metal band is also very nice, although it’s a bit tight for my wrist.

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