Preflight Checks

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 Canister tries to help you as much as possible by detecting any missing, outdated, inconsistent, or incomplete drivers when LTO hardware is detected.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 move on to Archive mode.
An orange (🟠) status indicates you're not 100% up to date, but fine to continue as is.
A red indicator (🔴) means you're blocked. Preflight Checks will tell you how to resolve it, if possible.


Since Big Sur's release, Apple no longer ships drivers for Host Bus Adapters, or HBAs. HBAs are the intermediate devices between your Thunderbolt device and the LTO SCSI device. Every Thunderbolt LTO drive ships with one:
  • 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 Areca's.
  • 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.
The Host Bus Adapter 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.
We've tried to smooth out the process as much as possible but be prepared for a bunch of successive reboots 🤷‍♂️
Canister detects an mLogic device, but no HBA is found.

MagStor & mLogic

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.

Other Vendors

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 Catalogs

To install the drivers needed for Catalogs, first you'll need to install Apple's Command Line Tools ("CLT"). Preflight Checks should prompt you to do so.
Preflight Checks prompting to install Command Line Tools
If not, you can do so manually with this Terminal command:
xcode-select install
Then, continue with the Catalogs installer.
Preflight Checks prompting to complete

"The Installation failed."

Sometimes, the Catalogs installer won't finish properly, stating the installation failed.
If so, CLT most likely wasn't installed properly, or is incomplete. 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.
Still unsuccessful? Send us your Catalog installer log:
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.

Installing kernel extensions

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. Then, a reboot is needed. Don't see the Allow button? Continue here: https://docs.hedge.video/canister/installation#dont-see-an-allow-button
On Apple silicon, you'll need to set your Mac's security policy to "Reduced Security" to be able to load signed kernel extensions:
  • Open the Security & Privacy preference pane, and Enable system extensions.
Enable system extensions
Shutdown to boot into the Security Utility
  • Shut down your Mac.
  • Hold down the power button until your Apple silicon Mac boots.
  • You'll either find yourself in macOS Recovery, or you'll see an Options button leading to that.
  • Log in with your user account and select the disk you want to use.
  • Click Security Policy...
Select the disk and click Security policy
  • In the menu bar, under Utilities, select Startup Security Utility
  • Select Reduced Security, and enable: Allow user management of kernel extensions from identified developers
  • Click OK
  • In the menu bar, select Shut Down.
  • Turn the Mac back on (not holding the power button this time) and log in.
  • After rebooting macOS should prompt to Open security Preferences . If this doesn't happen, open Canister which will tell you to Allow driver in system settings and trigger macOS into showing the much-coveted Allow button:
  • Click the lock bottom left-hand and enter your password.
  • Click Allow. You'll need to reboot once more, and then you're done.

Don't see an Allow button?

Look up your driver's name in /Library/Extensions first.


  • 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 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 to load. Talk to your IT department first, they'll know what to do.
Another option, when using ATTO drivers for 6G HBAs, is that you have a too old ATTO driver version installed. This typically happens when upgrading to a newer macOS. Canister tries to detect this, but sometimes it's not allowed to. If so, manually install the latest ATTO:

Still no success?

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, but 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 1d ago