As Apple rolls out macOS 15 Sequoia today, there’s a lot to be excited about. After months of rigorous testing across four separate OWC storage test labs, in addition to all the new features, we’re impressed by the significant improvements in this version related to storage. Apple has enhanced the overall reliability of storage hardware and the file system while dramatically reducing occurrences of kernel panics. For most users, macOS 15 Sequoia offers a smoother, more dependable experience than the previous version, Sonoma.
However, if you’re a 2019 Mac Pro user, there are some specific situations to be aware of. While the new OS offers many advancements, there are still some edge cases that may require holding off on the update or preparing for further patches. Let’s dive into what’s changed and what 2019 Mac Pro users need to know.
Overall improvements in macOS Sequoia
macOS Sequoia introduces several critical updates that boost system stability and performance, particularly for those handling large amounts of data or using advanced storage configurations. Key improvements include:
- Enhanced Storage Reliability: Apple’s tweaks have made the OS much better at managing storage hardware, reducing data management errors.
- Fewer Kernel Panics: Users will experience fewer unexpected crashes, thanks to better handling of storage and file system processes.
- Better File System Support: Apple has optimized file system operations, reducing instances where file access or data transfers cause system issues.
For most users, this means a significant step up in performance and stability, especially for those managing large files, creative projects, or complex workflows.
Great news for 2019 Mac Pro Users with OWC Accelsior 4M2s and 8M2s
If you are using macOS 14 on a 2019 Mac Pro with a PCI card with blades, you have probably started up your Mac at some point and had the volumes on the blades not appear. It’s not just the volumes that do not appear—the blades don’t either. System Report shows that the PCI card is installed, but according to macOS, the card contains no NVMe blades. The blades do not show up in Apple’s Disk Utility application or in SoftRAID. This “feature” was introduced with a new NVMe driver as part of last year’s macOS Sonoma.
This bug only affects Macs running macOS 14 and can occur with OWC Accelsior 4M2 and 8M2 cards as well as other cards like Sonnet 4×4 and 8×4 Silent cards. It occurs with any brand NVMe blade installed on the PCI card. Some users were able to work around it by booting first into Safe Mode and then booting immediately back into normal mode, while others have had to revert to macOS 13 (Ventura) before their blades would finally become available.
The great news is that this bug is now completely fixed in macOS Sequoia. Upon updating your Mac Pro to Sequoia, your blades should now always appear. No more booting into Safe Mode, no more rebooting countless times hoping your blades would show up. It (now) just works!
A warning for 2019 Mac Pro Users with Thunderbolt SATA enclosures
While many storage issues have been resolved in macOS Sequoia, 2019 Mac Pro users with external Thunderbolt SATA enclosures like the OWC ThunderBay 4 or ThunderBay 8 may run into a different problem.
During our extensive testing, we discovered that when running macOS Sequoia and accessing four or more SATA HDDs or SSDs simultaneously, the Mac can experience a system hang, leading to a kernel panic, automatic restart, and loss of all work which hasn’t been saved.
This issue seems to occur more frequently with faster, higher-capacity HDDs and SATA SSDs, and when multiple disks are being accessed at once—especially in RAID configurations. These kernel panics are particularly disruptive, as they lead to lost work and unexpected restarts. If this type of enclosure is core to your workflow, it’s advisable that you hold off on upgrading to Sequoia for the time being.
What’s next?
We have thoroughly investigated this issue with Thunderbolt SATA enclosures and know that it is a problem with the new SATA driver in macOS Sequoia. These hangs continue to occur, even if we prevent SoftRAID from loading.. In addition, when a hang occurs, the activity lights get stuck on for one or more drives, a clear indication that something has gone wrong with the SATA driver.
We have been able to reproduce this 100% of the time with certain makes and models of HDDs and SSDs by initializing four or more disks with SoftRAID, creating or deleting a volume, or converting between AppleRAID and SoftRAID volumes. If four or more disks are used, the hang and subsequent restart will occur.
We have reported this problem to Apple and are looking forward to a prompt resolution. Until then, we recommend that users with 2019 Mac Pros and Thunderbolt SATA enclosures exercise caution when running macOS 15, especially if they rely on accessing multiple high-speed SATA drives simultaneously.
It’s important to note that this problem does not affect USB3 enclosures like the OWC Mercury Elite Pro Quad.
We will update this post as soon as Apple releases a new version of macOS Sequoia that addresses the issue. You can also sign up for the SoftRAID Critical Issues email to be kept aware of SoftRAID updates, features, and more.
Conclusion
macOS Sequoia brings numerous enhancements that will benefit most users, especially those running storage-heavy workflows. However, if you’re using a 2019 Mac Pro, be aware of the resolved NVMe blade bug and the ongoing SATA driver issue. For most, the upgrade is smooth sailing, but for others, it might be worth waiting for the next release of macOS 15.
Stay tuned for updates, and feel free to reach out if you have any questions about how macOS 15 impacts your specific setup!
This is great news!
I have struggled with the missing blades problem in my MP2019 with Sonoma. It’s been hit or miss for the blades and very frustrating.
Not only that but RAID-1 mirror sets where only one blade of the RAID set appears, are extra unhappy.
You suggest that it is fixed with Sequoia. Great!
Do you know anything about Apple’s latest release on Sonoma 14.7? It was just released and I have high hopes…
The bug which prevents NVMe blades from appearing on a 2019 Mac Pro is only fixed in macOS 15.0 and later. It is not fixed in macOS 14.7 nor will it ever be fixed in any variant of macOS 14.
I NEVER update to a new OS until it’s revised to at least the v.1 or v.2 level. Over the last handful of years, Apple and Microsoft appear to have downgraded the first commercial release to a beta release, leaving the work of debugging the OS to their users.
Application developers like Adobe seem to have adopted a similar practice. In addition, they seldom have an adequately tested release that coincides with a new software release.
As always, upgrades are a balancing act for the use, is the risk of things being broken worth the bug fixes and new features it contains. For 2019 Mac Pro users who have been struggling for a year with blades which don’t appear, it is definitely worth upgrading.
Or better yet, use Disk Utility to create a new APFS volume in the APFS container which resides on the internal blade on your Mac. Then you can install macOS 15 on the new volume and switch back and forth between the two versions of macOS until you are certain the new one works with your key applications. this is what I have been doing for many years.