Poor Performance in Cluster Shared Volumes

João Seguro @ Chipcooler 15 Reputation points
2023-03-22T15:09:06.44+00:00

Hi All, 

I have noticed on several clusters upon which I've worked, that there is a huge fall off in the expected performance after LUNs added to the hosts are turned over into cluster shared volumes. With the LUNs attached to the hosts before clustering, I typically see the full performance afforded by the the network and the SAN.

However when the CSV is created on the storage, and local Virtual machines are moved into the cluster, the guests suddenly become more sluggish. Tests then reveal that the LUN's are not delivering their full performance. 
I had wondered if the management network performance then comes into play, but I'm unable to verify this after restricting associated ports to 10Gbps. Its strange however that we typically see this kind of performance degradation once the CSV's are created and none of the VM's I work on clustered seem to have stella performance now matter what the storage backing actually is.

Test scenario setup 

2 x DL380p Gen8 with 2 controllers 10Gbps

1 new san HPE 1060 SAN 4 x 10Gbe

Hosts connected to iSCSI in isolated network via 10Gbps port, with iSCSI on in its own switch.
Data Link Network not in use by Host OS.

The SAN typically gives 3 - 4 Gbps when served up as attached LUN's. Although I am not sure how this manages this speads over the iSCSI network mentioned above but however it does, and it maintains it over large files tested up to 100GB plus.

I have export some logs. In system logs, doesn't show anything.

Windows Server Clustering
Windows Server Clustering
Windows Server: A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.Clustering: The grouping of multiple servers in a way that allows them to appear to be a single unit to client computers on a network. Clustering is a means of increasing network capacity, providing live backup in case one of the servers fails, and improving data security.
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  1. Alex Bykovskyi 2,166 Reputation points
    2024-10-09T19:02:45.2+00:00

    Hey,

    CSV can have worse performance comparing to a simple iSCSI LUN. Especially, when you are testing performance on a node, which is not the owner of a CSV. https://learn.microsoft.com/en-us/answers/questions/857651/poor-cluster-shared-volume-read-write-performance.

    In addition, you should check that you have proper MPIO policy configured
    https://community.spiceworks.com/t/slow-csv-performance-on-windows-server-2016-failover-cluster/640765/3

    Might also help with troubleshooting:

    https://www.starwindsoftware.com/best-practices/starwind-virtual-san-starwind-benchmarking-best-practices/

    Cheers,

    Alex Bykovskyi

    StarWind Software

    Note: Posts are provided “AS IS” without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.

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