Installing SAS LTO drives

These ATTO interfaces add SAS ports to the Mac enabling control of a LTO tape drive or library

YoYotta suggests using SAS drives and libraries, both the drives and interfaces are more affordable.
SAS interfaces can connect more drives and they use more durable cables.
SAS has a simpler configuration and gives the same performance.

YoYotta can be used with Apple Silicon Macs or Intel Macs.
All macOS versions since Big Sur will need software drivers for SAS and FibreChannel interface cards and Thunderbolt LTO drives.
Thunderbolt units have a SAS LTO drive inside, so they will need a SAS driver.

ATTO SAS interfaces

LTO-1 to LTO-8 drives use 6Gb SAS interfaces, LTO-9 uses a 12Gb SAS interface. However with the correct cable any of these cards can be used for multiple tape drives as the maximum data rate for LTO-5 to LTO-9 of 140MB/s to 450MB/s is still less than 6Gb/s.

ATTO SAS RAID cards like the R680 are not supported, see the bottom of this page for more information.


The H680 is a PCIe 2.0 card with dual external connectors, each connector supports four SAS drives. The H680 supports TLR which is needed for LTO-7 onwards.
All other H6XX models can be used, like the H644 which has one external connector and one internal connector. Also the H608 which can be used with internal LTO drives.

With a regular SFF-8088 cable you can connect one LTO drive to each connector.
There are also 1 x SFF-8088 to 4 x SFF-8088 fan out cables, with these each connector can support four LTO drives. (No drop in performance).
Put the card in a Thunderbolt expansion like the Sonnet Echo Express SEL shown here.

Note that with the correct cables the ATTO H6XX cards could control eight LTO drives, however the PCIe bandwidth will not be enough to keep them all running at full speed. So you may need two SAS interfaces or update to the H1280GT.
YoYotta v4 subscriptions can be configured for between one and eight LTO drives.

The ATTO H680 is a great card and it is still fully supported, however it has been replaced by the H1280GT, so it might not be available.

ATTO H1280 + H1280 GT

The H1280 is a PCIe 3.0 card with TLR support and two 12Gb SAS connectors, it has been replaced by the H1280GT.
The H1280 GT model is a PCIe 4.0 card with TLR support and two 12Gb SAS connectors.
All other H12XX models can be used, like the H1244 which has one external connector and one internal connector. Also the H1208 which can be used with internal LTO drives.
Each 12Gb connector has four SAS ports, so with a fan-out cable each connector supports four LTO drives.
The higher speed of 12Gb/s isn't required for LTO drives, but it is fully compatible.

Desktop and most library LTO drives connect using SFF-8088 connectors.
For these you can get 1 x SFF-8644 to either 1 x SFF-8088 or 4 x SFF-8088 fan-out cable.
The LTO drives in some libraries like the Quantum i3 and i6 connect using SFF-8644 connectors.
For these you can get 1 x SFF-8644 to either 1 x SFF-8644 or 4 x SFF-8644 fan-out cable.

With the correct cables the ATTO H1280GT card can control up to eight LTO drives.
YoYotta v4 subscriptions can be configured for between one and eight LTO drives.

ATTO SH 3128

The ThunderLink SH 3128 is a Thunderbolt 3 adaptor that supports TLR and has two 12Gb connectors. These connectors connect to drives using SFF-8644 to SFF-8088 or SFF-8644 cables and work the same way as described above for the H1280GT.

The ATTO Thunderlink SH1068, SH2068 SAS interfaces are not recommended. See the section below about unsupported interfaces.

ATTO SAS install

Keep the card updated. To update ATTO firmware use an Intel Mac. The PCIe card can go inside a Thunderbolt expansion like the Sonnet Echo Express SEL shown here.
The Sonnet Echo Express SEL is a compact Thunderbolt enclosure that holds a PCIe card like the ATTO H680. A lot of our customers use this to connect to a desktop SAS LTO drive or tape library. Get the Thunderbolt 3 unit as this means that there is plenty of bandwidth for multiple LTO drives and also daisy chaining other Thunderbolt units. The Apple TB3 -> TB2 adaptor allows connection to older Thunderbolt 2 Macs. There are also other units that hold more than one card.

ATTO ThunderLink SH1068, SH2068 TB-SAS, ThunderStream SC3808, SC4808 adaptors, R680 or R644 PCIe RAID SAS cards do not support TLR which is a required protocol. So they are not compatible with LTFS running on any operating system.
These interfaces are not compatible with tape drives as they do not support TLR protocol. As a temporary workaround when using with LTO tape drives with these interfaces the link speed should be set to 3Gb/s. However there may still be errors. See section at bottom of this page.

Checking hardware devices

To check that the Mac can see the ATTO and LTO hardware hold the alt key on the Mac keyboard, click the Apple Menu and select System Information...

Check for PCI devices

If using an ATTO card inside a Thunderbolt chassis, then select PCI from the left hand Hardware list. The ATTO SAS card should be shown.

Check for Thunderbolt devices

If using an ATTO card in an expansion chassis, or you have a Thunderbolt LTO drive, then click Thunderbolt. Here the Sonnet Echo Express Pro is connected to the Mac. If there is no Thunderbolt device, then try reconnecting or using a different Thunderbolt cable. Also power cycle the Mac, interface and drive.

ATTO Driver missing or blocked

Now select SAS from the Hardware list. Here the driver has not been installed so no devices are shown. On newer macOS versions the driver may also be blocked, see the next section.

If missing then download and install the Mac driver (See ATTO SAS install above for links) Then reboot the Mac.

Note that Thunderbolt drives have a SAS tape drive and SAS interface inside, so they will need a SAS driver from ATTO or Areca. Contact your hardware supplier to find out what driver is needed for the SAS card is fitted to your LTO drive.

Allow system software in System Security

The first time after you install ATTO drivers on a new system, you will need to approve the new System Software. New installs of system software from YoYotta, ATTO, macFUSE (developer is Benjamin Fleischer) and other drivers may need approval.
You will see a message like this saying System Extension Blocked
Open the Security & Privacy page in Apple System Settings or Preferences, unlock the padlock and click Allow to enable the System software to load.

You must click the Allow button locally on the Mac, clicking using remote screen sharing will not work.
If the Allow button is not shown then reboot your Mac, try again to use an LTFS tape (which will fail) and then check the Security & Privacy page again.
Also ensure that you have the latest macOS 10.13.6, 10.14.6, 10.15.7, 11.6.5 or latest Monterey

Files and Folders access

When running YoYotta with newer macOS versions you may see requests to allow access to folders like Documents, Removable Volumes or Network Volumes. Please allow these requests.
Also you can enable access in Files and Folders in the Security tab as shown in the screenshot.
YoYotta does not need Full Disk Access.

ATTO Driver installed

Now the driver is installed and the ATTO ExpressSAS device is shown. No tape drives are connected.

LTO drive connected

Make sure an LTO drive is connected and powered on, now a SCSI Target Device @ 0 is shown. Here an IBM LTO-5 drive is connected.
YoYotta will now be able to control this drive.
The System Information page does not refresh automatically. Click File, Refresh Information or Command + R to refresh the hardware listing.

LTO library connected

Here an HPE MSL4048 with three LTO drives is connected. SCSI Target Device @ 1 has two logical units. The first is an LTO-5 drive, the second is the library robot. If two logical units are not shown then the configuration of the tape library needs to be set to allow external control. Check the settings for the control path, which are normally in the partition settings, using the library web browser interface.
SCSI Target Devices 2 and 3 are LTO-5 and LTO-4 drives.

The YoYotta Library option will now be able to control this library.

SAS troubleshooting

If jobs stop with errors like these, first check that the path in the error includes LTFS. If it does not then you need to check the source or destination drive, NAS or SAN.

Problem writing file 'Socket is not connected' (57)
Problem writing file 'Input/output error' (5)

These errors are low level issues sent from macOS that do not give much more information other than writing to the tape has failed.
This could be a SAS/FC interface, LTO drive or tape issue, to troubleshoot follow these steps.

  • Eject all tapes
  • Download the macOS Config Tool, driver and Flash Bundle from the ATTO website
  • Install the Config Tool and the macOS driver
  • Run the ATTO Config Tool, check and update the card firmware
  • Reboot the drive and Mac
  • Run test archive jobs from a local SSD to a new tape
If any issues Open the ATTO Config Tool and click Run Diagnostics in the Help menu. This will take some time to collect and save diagnostic logs.
Also save a copy of the YoYotta log + debug as described here
Then send both logs to and we will help you troubleshoot the issue.

Unsupported ATTO SAS interfaces

The ATTO Thunderlink SH1068, SH2068 TB-SAS, ThunderStream SC3808, SC4808 adaptors and the R680 or R644 PCIe RAID SAS cards do not support TLR, so there will be issues when controlling LTO-6, LTO-7 and LTO-8 drives.
These interfaces are not supported as they do not work with LTFS.
Files are written correctly, but when read back there are undetected soft errors. So the errors would be missed if the copy was not verified. If you get any verification issues, then check these settings.
The H680, H1280 and H1280GT SAS cards are not affected.

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