Daisy Chain

You can connect multiple LightBridge 2 ACL devices in a daisy chain.

 

Maximum Number of LightBridge 2 ACL in a Daisy Chain

 

According to the Thunderbolt™ 2 specification, maximally 6 LightBridge 2 ACL devices can be connected in a daisy chain. The actual number of LightBridge 2 ACL devices you may integrate into a daisy chain depends on the BIOS of your host PC.

   

Shared Bandwidth

The maximum DMA transfer rate of LightBridge 2 ACL is ≈ 1360 Mbyte/s. Which kind of cable you use (1 m, 2 m, 30 m optical, 60 m optical) has no influence on this value.

However, if you connect multiple LightBridge 2 ACL devices in a daisy chain, this DMA transfer rate is shared between the individual LightBridge 2 ACL devices.

Total below Maximum

As long as the total transfer rate of all LightBridge 2 ACL devices in the chain is less than 1360 Mbyte/s, you can allot the individual transfer rates quite freely.

Example (with six LightBridge 2 ACL devices connected):

 

LB1
[Mbyte/s ]

LB2
[Mbyte/s ]
LB3
[Mbyte/s ]
LB4
[Mbyte/s ]
LB5
[Mbyte/s ]
LB6
[Mbyte/s ]
Total transfer rate of all LBs
6 devices
(example allotment 1)
200 200 200 200 200 350 1350
6 devices
(example allotment 2)
100 100 450 100 100 450 1300

Total above Maximum

If the total transfer rate of all LightBridge 2 ACL devices in the chain is higher than 1360 Mbyte/s: The bandwidth available for each LightBridge 2 ACL device is allotted as follows, depending on the number of LightBridge 2 ACL connected to the chain:

 

LB1

LB2
LB3
LB4
LB5
LB6
Total transfer rate of all connected LBs
2 devices 50% 50%         100%
3 devices 50% 25% 25%       100%
4 devices 50% 25% 12,5% 12,5%     100%
5 devices 50% 25% 12,5% 6,25% 6,25%   100%
6 devices 50% 25% 12,5% 6,25% 3,125% 3,125% 100%

 

Actual values in Mbyte/s as verified with a MacMini PC running Windows:

 

LB1
[Mbyte/s ]

LB2
[Mbyte/s ]
LB3
[Mbyte/s ]
LB4
[Mbyte/s ]
LB5
[Mbyte/s ]
LB6
[Mbyte/s ]
Total transfer rate of all connected LBs
2 devices 684,8 684,8         1369,6
3 devices 684,8 345,6 345,6       1369,6
4 devices 684,8 345,6 172,8 172,8     1369,6
5 devices 684,8 345,6 172,8 86,4 86,4   1369,6
6 devices 684,8 345,6 172,8 86,4 43,2 43,2 1369,6

Examples for Overflow scenarios:

 

LB1
[Mbyte/s ]

LB2
[Mbyte/s ]
LB3
[Mbyte/s ]
LB4
[Mbyte/s ]
LB5
[Mbyte/s ]
LB6
[Mbyte/s ]
Total transfer rate of all LBs
Bandwidth required by devices 200 100 450 100 100 450 1400
Actually transferred Bandwidth 200 100 450 100 100 410 1360

At the sixth LightBridge 2 ACL device in the chain, an overflow occurs. Only ≈ 410 Mbyte/s are transferred from this device to the host PC.

 

LB1
[Mbyte/s ]

LB2
[Mbyte/s ]
Total transfer rate of all LBs
Bandwidth required by devices (2x CL FULL) 800 800 1600
Actually transferred Bandwidth 800 560 1360

At the second LightBridge 2 ACL device in the chain, an overflow occurs. Only ≈ 560 Mbyte/s are transferred from this device to the host PC.

Connecting LightBridge 2 ACL Devices in a Daisy Chain

To connect multiple LightBridge 2 ACL devices physically, use Thunderbolt™ technology port B on the rear side of the chassis:

  1. Use a Thunderbolt™ technology cable to connect Thunderbolt™ technology port B of a LightBridge 2 ACL device with the Thunderbolt™ technology port A of the next LightBridge 2 ACL device in the daisy chain:

Rear Side with port A for connection to host PC via Thunderbolt™ technology cable

  1. Connect each LightBridge 2 ACL device to the power supply unit.
  2. Connect the power supply unit to the power outlet.

Rear side with power connector