Enable SMB 3.1.1 multichannel on AKSUbuntu-1804containerd

[datwelk]

What happened:
An AKS node running AKSUbuntu-1804containerd-2021.07.25 with 5.4.0-1055-azure kernel uses SMB version 3.0.

What you expected to happen:
If an Azure File Storage account has SMB multichannel enabled, I expect the AKS cluster nodes to also use SMB 3.1.1, which is a minimum requirement from the server side to use the SMB multichannel functionality (see: here)

How to reproduce it (as minimally and precisely as possible):
N/A

Anything else we need to know?:
How do I enable SMB multichannel on Linux AKS node clients?

Environment:

• Kubernetes version (use kubectl version): 1.19
• Size of cluster (how many worker nodes are in the cluster?): N/A
• General description of workloads in the cluster (e.g. HTTP microservices, Java app, Ruby on Rails, machine learning, etc.): microservices
• Others: N/A

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[datwelk]

Kubernetes Volume docs specifically mention only SMB 2.1 and 3.0: https://kubernetes.io/docs/concepts/storage/volumes/#azurefile.

This could explain why 3.0 is used. Does SMB 3.1.1 require the azureFile CSI driver over the 'in-tree plugin'?

[andyzhangx]

if you are using Azure File CSI driver on aks 1.21+, it's already using vers=3.1.1 by default, Linux version 5.4.0-1063-azure

[andyzhangx]

it seems Linux version 5.4.0-1063-azure does not support -o multichannel mount options:

[914489.007018] CIFS: Attempting to mount //xxx.file.core.windows.net/pvc-359e202c-9bb3-4217-b022-480a863af014
[914489.007054] CIFS: Unknown mount option "multichannel"
[914493.542743] IPv6: ADDRCONF(NETDEV_CHANGE): azv784e8f3bb062: link becomes ready
[914493.542777] IPv6: ADDRCONF(NETDEV_CHANGE): azv784e8f3bb06: link becomes ready
[914493.543530] eth0: renamed from azv784e8f3bb062
[914505.124755] CIFS: Attempting to mount //xxx.file.core.windows.net/pvc-359e202c-9bb3-4217-b022-480a863af014
[914505.124802] CIFS: Unknown mount option "multichannel"

[datwelk]

It seems this was added to the linux 5.5 kernel [source]

Would it be possible to double check this with the team responsible for the Azure linux kernel, and ask when the changes from 5.5 will be incorporated?

[andyzhangx]

5.5+ will come only with 20.04, we will support 20.04 in near future, thanks.