Cohesity Cluster Architecture

31 January 2025

This section describes the components that make up a Cohesity cluster.

Nodes

A Cohesity node contains CPU with spinning disk or flash storage that is preinstalled with the Cohesity software. A Cohesity cluster can be hosted on:

Datacenters: Running on x86-based server consisting of three or more physical nodes.
Edge: A single node ROBO running on x86-based physical servers or a Virtual Edition cluster running on hypervisor with a single node or multiple nodes, depending on the hypervisor.
Public Cloud: Cloud Edition Cohesity cluster deployed on public clouds like Amazon Web Services, Microsoft Azure and Google Cloud Platform.

A node can be in one of the following states:

Available on the Network but not assigned to the cluster
Assigned to the cluster

Storage Domains

A Storage Domain, formerly known as a View Box, is a named storage location on a cluster. At the storage domain level, settings like fault tolerance, encryption, and storage efficiencies are applied. A Storage Domain contains Views. When you configure a Protection Group, you specify a Storage Domain and during a Protection Group Run, the Cohesity cluster stores the Snapshots in that Storage Domain.

If Deduplication is on, the Cohesity cluster eliminates duplicate blocks of repeating data stored on the Cohesity cluster, thus reducing the amount of storage space needed to store data. You may want to disable deduplication and here are some possible reasons:

The speed of backing up on the Storage Domain is more important than conserving the disk space used to store the Snapshots or files. For example the Storage Domain contains a View and you want fast writes to that View (Datastore).
You are storing backups on the Cohesity cluster that were created by another backup product that already deduplicates the data.

If Inline Deduplication is on, deduplication occurs when the Cohesity cluster writes the data to the Cohesity View. If Inline Deduplication is off, deduplication occurs after the Cohesity cluster writes the data to the Cohesity View.

Views

A Cohesity view provides a storage location with one or more of these protocols namely NFS, SMB, S3 and SWIFT in a storage domain on the Cohesity cluster.

The NFS mount path can be mounted onto systems using the NFS protocol. The SMB mount path can be mounted onto systems as an SMB share.

You can use the view to store data such as files, backup snapshots, and cloned VMs. Views can only be mounted on any machines specified in the allowlist subnets. A view also acts as a datastore during the VM cloning process and during VM recovery. You can select the SWIFT protocol and a create SWIFT-only view for OpenStack environments.

You can create a view for the following three categories:

File Shares
Backup Target
Object Services

You can select the Read/Write protocol and, optionally, select the Read-only protocol.

You can create a Cohesity view only by using a template. The template can be a predefined template or a custom template. For more information, see:

If you are using Kerberos (AD or MIT), you must create a view using the same storage domain that is mapped to AD/MIT-Kerberos + LDAP.

For more information, see Create Views Using a Predefined Template and Add Subnets to Allowlists.

Views can be used to store data such as files and directories. For example, other backup products can store data on a view that is hosted on the Cohesity cluster. To access a view from your system, you must mount the view.

The table below summarizes the features at the storage domain and view levels, and how they are inherited.

Features	Storage Domain	View
Fault tolerance	Erasure Coding (EC) Replication Factor (RF)	Inherits storage domain fault tolerance settings and cannot be changed for the View.
Storage efficiency	Deduplication (inline, post-process, or disabled) Compression (inline, post-process, or disabled)	Inherits storage domain efficiencies OR Can be overwritten at the View level to be post-process if at the storage domain level is inline, but cannot be disabled.
Encryption	Enabled or disabled	Inherits storage domain's settings and cannot be changed for the View.
Cloud Tier	Inherits cluster settings, unless overwritten at the storage domain level.	Inherits storage domain's settings and cannot be changed for the View.
QoS Policy	N/A	Set for each View.

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