The CVM (Controller VM) CPU core and memory requirements in Nutanix environments are determined by a couple of key parameters:

Total Capacity

• The overall storage capacity of the node influences the number of CPU cores and the amount of memory allocated to the CVM.
• Higher capacity nodes require more resources to manage storage operations efficiently.

Recovery Point Objective (RPO)

• The RPO, which defines the acceptable amount of data loss in case of a failure, impacts the CVM resource allocation.
• Lower RPOs require more CPU cores and memory to ensure data replication is quick and accurate.

For the actual resource requirements refer to HCI Node Capacity & CVM Resource Requirements.

CVM Storage Overheads

Key Parameters for CVM Storage Overhead:

• Nutanix Boot + Home: 280 GB across 2 drives, always on Tier-1
• OpLog: 600 GB, Tier-1
• Hades Reservation: 100 GB per disk, irrespective of disk type
• Cassandra: 3% of all drives, are always on Tier-1 storage
• Curator: 2% of all drives, are always on Tier-2 storage
• Ext4 Formatting: Varies by storage type (HDD, SSD, NVMe)

CVM Storage Overhead Summary:

Nutanix Boot + Home:

• Overhead: 280 GB across 2 drives
• Tier: Always on Tier-1 Storage

OpLog:

• Overhead: 600 GB
• Tier: Always on Tier-1 Storage
  

  Hades Reservation:

• Overhead: 100 GB per disk
• Tier: Irrespective of disk type
  

  Cassandra:

• Overhead: 3% of all drives
• Tier: Always on Tier-1 Storage

Curator:

• Overhead: 2% of all drives
• Tier: Always on Tier-2 Storage
  

  Ext4 Formatting:

• HDD: 1.78% of drive size
• SSD & NVMe: 2.6% of drive size

The overheads can be seen in Sizer by hovering over the info icon as seen below: