Installing ATTO SAS or FC interfaces

These ATTO interfaces add SAS or FC 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 runs well on the new Apple Silicon M1 Macs and Big Sur.
Any Mac running Big Sur will need new software drivers for SAS and FibreChannel interface cards and Thunderbolt LTO drives.
MagStor have released new drivers for their Thunderbolt 3 LTO drives and we have tested them with M1 Macs.
ATTO have released new drivers for their interfaces and these have also been tested with M1 Macs.

ATTO SAS interfaces

LTO-1 to LTO-8 drives use 6Gb SAS interfaces, so with the correct cable any of these cards can be used.

ATTO SAS RAID cards like the R680 are not supported, see the bottom of this page for more information.
The ATTO H680 is discontinued, so it might not be available.

ATTO H680

The H680 is a PCIe 2.0 card with dual external connectors, each one supports four SAS drives. The H680 supports TLR which is needed for LTO-7 and LTO-8.
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 whilst the ATTO interface could control eight LTO drives, YoYotta LTFS supports two LTO drives and YoYotta Automation supports four LTO drives.

ATTO H1280 + H1280 GT

The H1280 is a PCIe 3.0 card with TLR support and two 12Gb SAS connectors.
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 four LTO drives are supported.
The higher speed 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.

Note that whilst the ATTO interface could control eight LTO drives, YoYotta LTFS supports two LTO drives and YoYotta Automation supports four 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 H1280.


ATTO SAS install

Keep the card updated. The PCIe card can go inside a MacPro with PCIe slots or in 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.


ATTO Fibre Channel (FC) interfaces

FC LTO drives have 8Gb/s interfaces.
Unlike SAS each FC connector only supports one drive.

If the drive has a Fibre Channel connection there are ATTO FC81 / FC82 / FC84 PCIe FC PCIe cards.
Use an ATTO FC card in a Sonnet Echo Express Thunderbolt3 chassis.
There are also TLFC-2082/2162 Thunderbolt2 to FC interfaces, they have 2 FC connectors so they can only control 2 drives.

The TLFC-3162 and TLFC-3322 Thunderbolt 3 FC adaptors do not support LTO drives.
Note that the ATTO multipath driver does not support tape drives.
Download and install the latest Mac driver and card firmware from the Fibre Channel HBA downloads.

  • Download the macOS Configuration Tool, macOS driver and macOS Flash Bundle
  • Install the Config Tool and the macOS driver
  • Run the ATTO Config Tool and update the card firmware

The PCIe card can go inside the older MacPro or in a Thunderbolt expansion like the Sonnet Echo Express SEL shown here.

Here are the recommended settings in the ATTO ConfigTool.
  • Use the standard ATTO FC driver NOT the ATTO multipath driver
  • Enable Native Multipathing
If you have problems mounting or formatting tapes.
  • Maximum I/O Transfer Size – 1 MB (change from Default)


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 MacPro, 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 or Fibre Channel 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 for the H680 from the ATTO website. Then reboot the Mac.
Note that Thunderbolt drives have a SAS adaptor inside, so they also need a driver from ATTO or Areca.


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. Also new installs of system software from YoYotta, ATTO, OSXFUSE (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 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 or 11.2.3


Files and Folders access

With Catalina and Big Sur when running YoYotta 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 here.
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 LTFS 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 @ 0 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 using the library browser interface the settings for the control path, which are normally in the partition settings.
SCSI Target Devices 1 and 2 are LTO-5 and LTO-4 drives.
This is a SAS library, check the Fibre Channel entry for a FC library.

YoYotta Automation will now be able to control this library.


SAS or FC 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 ATTO SAS downloads
  • 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 support@yoyotta.com 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 and H1280 families of SAS cards ares not affected.

To reduce the errors, set the PHY link speed to 3Gb/s rather than Auto or 6Gb/s.
This is a temporary workaround until you replace the units with an ATTO H680, H1280 or SH3128.

With the SH2068 use the Jan 2016 firmware, file name is osx_fls_tlsashbab_160129.dmg, do NOT use the newer Jan 2017 firmware.

To do this open the terminal app and type this to display the current R680 settings.
/Applications/ATTO/ExpressSASRAID2/atsasnvr -p

Or type this to display the current ThunderLink settings.
/Applications/ATTO/ThunderLinkSASHBA/atsasnvr -p

Then type one of the following to change the link speed.
/Applications/ATTO/ExpressSASRAID2/atsasnvr -k 3
/Applications/ATTO/ThunderLinkSASHBA/atsasnvr -k 3

Power cycle the ATTO and restart the Mac.
Then type the first command again to check the new settings they will show PHY Speed: 3 Gb/s

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