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There is an Intel feature called SNC or COD. SNC does not stand for Secure Network Connection, but for Sub-NUMA Clustering. COD does not stand for a video game, but for Cluster-On-Die.

These features are used in newer hardware and have been partially activated by default for around two years (for example at HPE).

The features may not be used with HANA under any circumstances. In addition to performance problems, inconsistencies can also occur!

A physical NUMA node is divided into two NUMA nodes. During one of our HANA health checks, not only the database but also the storage, hypervisor and OS are checked. We noticed at one customer that the ESXi suddenly shows 4 NUMA nodes on a physical 2 socket server.

At ESX level, this can be checked with the following command:

echo "CPU Packages";vsish -e dir /hardware/cpu/packageList;echo "NUMA nodes"; vsish -e dir /hardware/cpuTopology/numa/nodes

The feature can be deactivated in the BIOS (example HPE).

Source

2470289 - FAQ: SAP HANA Non-Uniform Memory Access (NUMA):

Is it possible to use sub-NUMA clustering for SAP HANA?

On BIOS/UEFI level it is possible to define more than one NUMA node per CPU socket (Intel Cluster-On-Die (COD) / sub-NUMA clustering technology). This scenario isn’t supported and can result in SAP HANA persistence corruptions (SAP Note 2116157).

2116157 - FAQ: SAP HANA Consistency Checks and Corruptions

"Unsupported activation of Intel Cluster-On-Die (COD) / sub-NUMA clustering technology"

Details:

Sub-NUMA Clustering by Frank Denneman