Using LTO on a Mac requires a range of drivers to be all properly installed. Getting your drivers sorted out can be a bit of a hassle, especially on Big Sur and later macOS versions. Canister's Preflight Checks functionality tries to help you as much as possible by detecting any missing, outdated, inconsistent, or incomplete drivers when LTO hardware is detected.
Upon each app start, Canister will do a complete systems check - looking for Thunderbolt devices, Host Bus Adapters, and SCSI devices. On the software side, Canister checks for all required frameworks and drivers. Canister will also offer to download Apple's Command Line Tools ("CLT") and a separate installer for the Catalog functionality.
🟒 Everything green - you're good to go, and Canister will automatically continue.
🟠 Orange indicates a part of your setup is not 100% up to date, but it's fine to continue as is.
πŸ”΄ Red means your setup is incomplete. Preflight Checks will tell you how to resolve it, if possible.

Each LTO drive that uses Thunderbolt actually consists of three devices: the Thunderbolt-to-PCI board, a Host Bus Adapter (translating PCI to SCSI), and the LTO drive itself. If you're using a SAS LTO Drive, your HBA will live in an external box or as a PCI card inside your computer.
Since Big Sur's release, Apple no longer ships drivers for the HBA. The HBA drivers are macOS kernel extensions. Starting with Big Sur, kernel extensions require additional steps to be used. On top of that, Apple silicon devices require additional security settings to be set in order to allow those extensions to run. This is regular behavior, but cumbersome nonetheless.
  • Most brands, including recent mLogic units, use ATTO. To make matters easy, there are three possible ATTO drivers: 6G, 12G PCI-3, and 12G PCI-4 ("GT").
  • MagStor mostly uses Areca but sometimes ATTO. Old mTape units are also housing Arecas.
  • Some brands might use SANPoint or HighPoint HBAs.
  • LSI HBAs do not work on a Mac. These cards are also sold under HP's brand name.
We've tried to smooth out the process as much as possible but be prepared for a bunch of successive reboots and raised eyebrows πŸ€·β€β™‚οΈ
Canister detects an mLogic device, but no HBA is found.

If you have a mLogic or MagStor Thunderbolt device, Canister will ask you for its serial and provide the correct driver for the HBA. Locate your serial on the back or bottom of your unit.
Locate your mLogic or MagStor serial on the back or bottom of your unit.

Symply exclusively uses ATTO HBAs, but the model varies with the unit. Best to reach out to Symply first - they will know, and will be able to get you up and running.

Open World Computing's Mercury LTO devices have used various HBAs, including LSI units that do not work on a Mac. Reach out to OWC to learn which driver you'll need.

If you're using a different brand, Canister does an educated guess if no HBA is detected (thus no driver is installed). If you don't know which driver your LTO hardware needs, get in touch with your vendor - they know, and will be able to get you up and running.
Installing HBA drivers can be a tedious ordeal. Refer to the "Installing kernel extension" section on this page for troubleshooting.

To make life easy, here's a list of all drivers that we host. You shouldn't be needing these links if you're using Canister, but sometimes it helps to have direct access.
We keep these drivers up-to-date at all times, so no need to worry about checking if they're the latest version.

Now that you have installed your HBA drivers, it's onto LTFS. First up is macFUSE, which LTFS uses to represent the data onto the tape as a volume on your computer. It's a kernel extension so yes, more reboots.
Then, if Canister detects an HBA and LTO drive, it will deduce which LTFS and ICU drivers you need, and prompt you to download these. When that's done, finally you'll need some additional drivers for Canister's Catalogs functionality.
To install the drivers needed for Catalogs, first install Apple's Command Line Tools ("CLT"). Preflight Checks should prompt you to do so:
Preflight Checks prompting to install Command Line Tools
If CLT doesn't download (it happens, as Apple hosts it themselves) you can do so manually with this Terminal command:
xcode-select install
Then, continue with the Catalogs installer.
Preflight Checks prompting to complete

Sometimes, macOS won't properly finish the Catalogs installer, stating the installation failed. If so, CLT most likely wasn't installed properly or is installed incompletely. Reinstalling CLT will fix that:
  • Delete the folder /Library/Developer/CommandLineTools. If not present, CLT isn't installed anyway.
  • Reinstall Command Line Tools by using the following Terminal command:
xcode-select --install
  • Run this command to make sure the installation is correct (all on one line):
PATH="/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/libexec"; export PATH; m4 --version
  • The Terminal output should look like this:
GNU M4 1.4.6 Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Written by Rene' Seindal.
  • Then, rerun the Catalog installer.

1. Right after installation, go to Finder and hit Shift-Command-G
2. Go to /tmp
3. Locate the canister-catalog-installer.log file, and email that to us.

If your Mac is managed through MDM, contact your System Administrator. The following steps below will not apply when using MDM.
First, install the required HBA driver and/or macFUSE.
On Intel Macs, you'll see an Allow button in System Preferences > Security & Privacy. Click the button, enable the kernel extension if asked for, and then reboot.
Don't see the Allow button? Continue here: If you don't get an Allow button to show up for your driver​
On Apple silicon, you'll first need to set your Mac's security policy to "Reduced Security" to be able to load signed kernel extensions:
1. In System Preferences, go to the Security & Privacy preference pane and click General.
2. Next, click Enable system extensions..., then click Shutdown when prompted.
Enable system extensions
Shutdown to boot into the Security Utility
3. Shut down your Mac.
4. Press and hold down the power button until your Apple silicon Mac boots. Your Mac will either send you directly into macOS' Recovery environment, or you'll see an Options button leading to that.
5. Log in with your user account and select the disk you want to use.
6. In the menu bar, go to Utilities, then select Startup Security Utility.
7. Click Security Policy...
Select the disk and click Security policy
8. Select Reduced Security, then enable: Allow user management of kernel extensions from identified developers .
9. Click OK.
10. In the menu bar, select Shut Down.
11. Turn the Mac back on (press but don't hold the power button this time) and log in.
12. After rebooting, macOS should prompt to Open Security Preferences .
If this doesn't happen, launch Canister which will tell you to Allow driver in system settings and trigger macOS into showing the much-coveted Allow button:
13. Click the lock bottom left-hand and enter your password.
14. Click Allow. You'll need to reboot once more, and then you're done.

First, look up your driver's name in /Library/Extensions :

  • For ATTO 6G, use ATTOExpressSASHBA2.kext
  • For ATTO 12G (PCI-3), use ATTOExpressSASHBA4.kext
  • For ATTO 12GT (PCI-4), use ATTOExpressSASHBA5.kext
Then, try loading the kernel extension manually in Terminal:
macOS 11 and newer
macOS 10.15.7 and older
sudo /usr/bin/kmutil load -p /Library/Extensions/ATTOExpressSASHBA2.kext
sudo kextload /Library/Extensions/ATTOExpressSASHBA2.kext
You'll need to enter your password. Then, open the Security & Privacy pane again – it should show you the Allow button.

For macFUSE, use this command in Terminal (all on one line):
macOS 11 and newer
macOS 10.15.7 and older
sudo /usr/bin/kmutil load -p /Library/Filesystems/macfuse.fs/Contents/Extensions/11/macfuse.kext
kextload /Library/Filesystems/macfuse.fs/Contents/Extensions/11/macfuse.kext
Again, you'll need to enter your password, then open the Security & Privacy pane – it should show you the Allow button.

If you finished the installation, and your LTO drive works but stops working after each reboot, forcing you to load the kernel extension over and over again, there's likely a remnant of an older ATTO driver of your system. Here's how to remedy that:
  • In Finder, hit Shift+Command+G and go to /Library/Extensions
  • Delete any ATTOSASHBA*.kext in that folder (password required, most of the time)
  • In Terminal, do sudo kextcache --clear-staging (password required)
  • Reboot if macOS doesn't already force you to.
  • Reinstall the ATTO driver your LTO machine requires.

If Terminal returns an error like system policy prevents loading and/or doesn't load macFUSE, your computer is very likely under IT management policies that prevent kernel extensions from loading. Talk to your IT department first, they'll know what to do.

When there's a problem with your hardware being detected, you're likely to run into one of two situations:

macOS doesn't detect a LTO SCSI device. Canister will keep scanning until it finds one.
  • If you have an mLogic device, your Thunderbolt cable probably isn't connected properly.
  • If you are using a LTO drive with a separate HBA, the HBA isn't detected. Install its driver first.

Your Mac somehow lost the connection to the LTO drive. If you know for sure all hardware is powered up, check if all devices are present in macOS. Launch System Information.app. You should see at least two entries:
  • Hardware > Thunderbolt: mTape, Sonnet, MagStor, etc.
  • Hardware > SAS: Ultrium, IBM, HP, Quantum
If you don't see an Ultrium LTO drive listed under SAS, power cycle the Thunderbolt device and the LTO drive. If you're still not seeing anything listed under SAS, restart your Mac.
Can't get up and running? Running in circles? It can happen and typically is an indicator of a deeper macOS problem. The company that sold you your LTO drive and/or Host Bus Adapter should be your first line of contact, as this is about your hardware - not Canister. That said, we're happy to help if that's a dead end as well.
Don't hesitate to contact us, and be sure to include a screenshot of Canister's Preflight Checks, so we know what the situation is before jumping on a call.
Last modified 1mo ago
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Preflight Checks
MagStor & mLogic
Other Vendors
If the Catalog installer states "The Installation failed."
Installing kernel extensions
If you don't get an Allow button to show up for your driver
If macOS doesn't keep the ATTO driver loaded after rebooting
System Policy issues
Still no success?