10 Gb iSCSI CSV performing at 1 Gb on Windows 2016 Hyper-V

We have a 2 host cluster with hyper-V based on Windows 2016 patched

We have a Fujitsu DX SAN 10 Gb iSCSI SAN as the primary storage, connected using 10 Gb SFP+ DAC connections to the servers

Both iSCSI networks are isolated from the rest of the environment.

We are using MPIO and 2 connections for the iSCSI configuration on each host

When the iSCSI volumes are configured and mapped with a network drive on a single host we get good performance moving things in and out of mapped drive, anything between 5-8 Gbps

The moment we add the same volume as a CSV to the cluster, performance drops drastically to 1 Gbps

We have been testing different configurations, disabling unnecessary protocols on the NICs and others.

Had a remote session with Fujitsu and they are pointing the finger at Microsoft

Is there any particular necessary configuration to get the full performance out of the CSV?
Ian TaylorIT Infrastructure Architect .:|:.:|:.Asked:
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Zaheer IqbalTechnical Assurance & ImplementationCommented:
Firstly, it is a by design issue that adding the disk to csv would cause it be much slower that the normal network drive.
Based on my researching, the VHDX operation with ReFS would be faster than the NTFS.

Here is the article which told ReFS acceleterated vhdx operations:

For more information about NTFS and ReFS, please refer to the following link:

Philip ElderTechnical Architect - HA/Compute/StorageCommented:
Once the CSV owner is established run a test from the owner node. Does it behave better?

Are there any Storage QoS settings enabled that would reduce throughput to 10%?
Ian TaylorIT Infrastructure Architect .:|:.:|:.Author Commented:
I have now updated the ISCSI NIC Drivers and changes the NIC profile settings which has resloved the issue.

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Ian TaylorIT Infrastructure Architect .:|:.:|:.Author Commented:
updated drivers and settings
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