Last Week on My Mac: SSD it

Last week I finally retired my 8 year-old Promise Pegasus RAID system, which has steadfastly stored my Time Machine backups on a succession of hard disks over those years. I’ve sort of replaced it with an SSD RAID, but it’s only sort of as Time Machine has now stopped working. Indeed, what should have been a seamless transition has turned into a bit of a mess: it’s still not really up and running in the way I had intended.

After mulling this over and discussing it here, I decided to move my backups onto an OWC ThunderBay 4 (Thunderbolt 3) containing 2 TB Samsung 860 EVO SSDs. In a bid to fool myself into believing that this wasn’t really going to cost me $/€/£ 1500, I quietly bought the first SSD late last year. Then I ordered the enclosure and another two SSDs, with the fourth due on Monday. I did have one heart-stopping moment just after I’d ordered the enclosure: I downloaded the ThunderBay user guide, only to read there that it was incompatible with Samsung 860 EVO SSDs, but a little investigation showed that had only applied to early versions which had shipped in 2018. The current model seems pretty omnivorous.

I opted to turn three of those SSDs into a single striped array (RAID level 0) using SoftRAID XT, a product which I had already relied on in the past. Once I had the SSDs and enclosure, it was just a few minutes work to install the drives and get ready to shut my old Pegasus down, ready for replacement.

SoftRAID 5.8.1 is stated as being “compatible with macOS Catalina 10.15”, but its support pages warn that “Catalina prevents the SoftRAID driver from being installed or updated when Secure Boot, (System Startup Security) is enabled.” So I knew that once I had installed SoftRAID, I’d have to restart with Secure Boot disabled so that the kernel extensions could be installed correctly. This was starting to become a bit more messy than I had expected, but hey ho.

What I then discovered, the hard way, is that on my iMac Pro running 10.15.3, I can only run with Secure Boot turned off. The moment that I restart with Secure Boot turned on, SoftRAID can’t find the required kernel extensions, tries to install them but can’t, so I have to force quit the app, restart in Recovery Mode, disable Secure Boot, then restart before I can use the app again. In fairness, this is mentioned in the release notes for version 5.8, which are installed alongside the app. Messier again.

Secure Boot isn’t so much of a loss now, perhaps. It’s a feature of T2-equipped Macs which ensures that they start up from a certified copy of macOS, and is separate from the option to boot from an external drive. As such its protection overlaps considerably with that provided by Catalina’s read-only System volume. So, for the moment at least, I can live with just the one.

SoftRAID is a delight to use. Configuring the three SSDs into RAID 0 took little more than the twinkling of an eye, and the app tells me that TRIM is enabled on all my SSDs and provides full access to those drives for SMART monitoring too. Those are valuable bonuses.


Despite the delays with Secure Boot, I was making good progress, and was ready to invite Time Machine to make its first full backup to the new drive. As this amounted to a little more than 1.2 TB, I was interested to discover how long it would take with 6 TB of striped SSDs. As I described in yesterday’s article, Time Machine didn’t back up. On at least six different runs, using slightly different tweaks and settings such as whether to include a backup of the System, it has stopped with only 215.90 GB backed up, and refused to go any further.

Unable to make any more progress with Time Machine, I fell back to Mike Bombich’s Carbon Copy Cloner, a friend from the more recent past than SoftRAID. As you’d expect, Carbon Copy Cloner behaves flawlessly and now backs up my Data and external volumes to the new SSD RAID. Excellent though it is, it’s not what I’d choose as a backup system to replace Time Machine completely, so I’ve been looking at alternatives including Acronis True Image, Arq, and ChronoSync. Of those, Econ’s ChronoSync looks the most promising. It’s a one-time purchase with free updates forever, and gets a lot of details right, even providing extensive release notes. I’ll let you know how I get on with it.

A great deal has changed since I installed my Pegasus RAID. Amazingly its kernel extension has remained compatible with macOS over those years, and still works fine with Secure Boot enabled. But if you were to ask me whether I’d recommend a regular user to try installing this setup on a current model of Mac with Catalina 10.15.3, I’d have to say no. I’m generally happy with Catalina, delighted with the ThunderBay 4 enclosure, and impressed with SoftRAID. But the sad fact is that – for whatever reasons, and I’m here not interested in blamestorming – they don’t work together. Yet. There are even moments when I wish my old Pegasus was still connected.