Understanding vSAN Redundancy Levels
Learn about VergeOS vSAN N+1 and N+2 redundancy levels, their requirements, use cases, and considerations
Overview
VergeOS vSAN supports configurable redundancy levels — also known as Replication Factors (RF) — that determine how many copies of each data block are maintained across the system. Choosing the right level is a balance between fault tolerance, storage overhead, and infrastructure cost.
N+1 Redundancy (RF2)
N+1 redundancy maintains 2 copies of every data block in the vSAN. This allows a cluster to survive one simultaneous failure — either a node failure or drive failures within a single node.
Minimum Nodes
2 controller nodes
Copies of Data
2
Storage Overhead
~2x (before deduplication)
When to Use N+1
VergeOS N+1 is the default configuration and well suited for most scenarios. It provides a strong balance between capacity efficiency and fault tolerance and is appropriate for many production environments when combined with best practices for data protection such as regular snapshots and off-site data replication.
For additional protection, a Repair Server can be configured to automatically attempt to retrieve missing data blocks from a sync destination if failures exceed the configured redundancy level, potentially avoiding a full snapshot rollback.
N+2 Redundancy (RF3)
N+2 vSAN redundancy is available for environments that have a specific requirement to maintain 3 copies of every data block and/or for a system to survive two simultaneous failures. N+2 can survive two simultaneous node failures, disk failures across two nodes, or a combination of both.
Minimum Nodes
3 (all controller nodes)
Recommended Nodes
5 (provides a witness node to completely avoid split-brain scenarios)
Copies of Data
3
Storage Overhead
~3x (before deduplication)
When to Use N+2
N+2 is designed for environments with a specific requirement to withstand more than one simultaneous failure. Common scenarios include ultra-critical workloads where even the brief exposure during a rebuild is unacceptable, or remote/edge sites where failed hardware cannot be replaced quickly. In these cases, the extra infrastructure cost of N+2 may be justified.
Per-Tier Redundancy
A failure only affects the tier where the failed drives reside. For example, in an N+2 configuration, if drives on Tier 1 fail on two nodes and a Tier 4 drive fails on a different node, the cluster remains fully operational, and no data is lost.
Configuring vSAN Redundancy Level
Redundancy level is typically configured during system installation.
Changing a System's Redundancy Levels
It is possible to upgrade an N+1 system to N+2 (provided the minimum node requirement is met). This transition involves a data rebalancing process.
To perform a redundancy level change, contact Verge.io Support.
Viewing Tier Redundancy Status
To check the current redundancy configuration and status of a vSAN tier:
Navigate to Infrastructure > vSAN Tiers from the top menu.
Double-click the desired tier to open its dashboard.
Locate the Status card:
Redundancy — Displays the configured redundancy level (e.g., N+1 with 2 copies, N+2 with 3 copies).
Redundant checkbox — Indicates whether the tier is currently meeting its configured redundancy level. This will be unchecked if any nodes or tier drives are down.
Quick Comparison
Copies of data
2
3
Simultaneous failures tolerated
1
2
Minimum controller nodes
2
3
Recommended nodes
3
5
Storage overhead (before dedup)
~2x
~3x
Default
Yes
No
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