link aggregation only in one direction useful?

[Marco Ertel]

Hi,
I tried out the link aggregation as I upgraded my machine with an additional network card with 4 Gbit Connections (Hardware Info at the end). My switch supports 802.3ad and I've set the 4 links to active link aggregation. In the NAS I've set LACP as protocol.
If I now test with iperf (two instances of iperf -s on different ports running directly on the NAS) with two machines connected to other ports on the switch I get interesting results:

• for traffic from the 2 computers to the NAS I get in sum around 1Gbit.
• for traffic from the NAS to the two computers I get around 1Gbit per computer

If I look in the reporting on the NAS it looks that in the first case (2 computers->NAS) only one link is used but for the outgoing traffic (NAS->2computers) two links are used.
I am doing something wrong? Do I have a wrong understanding?

Hardware:
Switch: D-Link DGS-1100-16V2 (Firmware actual 2.00.003)

NAS:
motherboard: Fujtsu D3417-B
Processor: Intel Xeon E3-1225v5
RAM: 32GB ECC
HD: 6*14TB Toshiba Enterprise MG07ACA SATA
one pool with RAIDZ2
network card: Intel i350-T4
Version: TrueNAS-12.0-RC1

Has somebody an idea?

Thanks and Kind Regards
Marco

 

[Elliot Dierksen]

Link aggregation is not bonding. That means that any single conversation can get no more than the bandwidth of a single link. Link aggregation is very useful for redundancy or serving multiple connections. It won't make a single connection go faster.

 

[Marco Ertel]

Link aggregation is not bonding. That means that any single conversation can get no more than the bandwidth of a single link. Link aggregation is very useful for redundancy or serving multiple connections. It won't make a single connection go faster.

That is clear. But I had used three machines:

• one with freenas (and running two commandlines with iperf3)
• one Desktop with windows
• one laptop with windows

Up to my understanding these are completely independent conversations or am I wrong here? And also the traffic outgoing from the NAS to the two machines was then near 2Gbit but incoming not (there it was only around 1Gbit).

Regards
Marco

 

[Elliot Dierksen]

Each side of the link uses a hashing algorithm to determine which member should carry the traffic. By default, most devices use the destination IP/MAC address. That works great from FreeNAS towards the client machines. It doesn't work from the client machines toward FreeNAS because it is a single destination IP/MAC address. If you the option in the switch, change the load balancing algorithm to use the source address on the link towards FreeNAS. That should give you a better distribution.