vSAN space reporting feature overview

Products

• VMware vSAN

Issue/Introduction

• This article describes the vSAN space reporting feature and the space usage data definitions shown in space reporting.

 

vSAN ESA Effective Capacity

• vSAN effective capacity is supported in vSAN ESA 9.1 and later releases, this feature provides an effective capacity of the datastore that includes:

1. 1. The total usable capacity, used capacity, and the free usable capacity.
   2. For clusters that have data reduction techniques such as vSAN ESA global deduplication and compression enabled, you can view the deduplication and compression savings and the deduplication and compression ratio.
   3. Overall data efficiency such as total provisioning and snapshot saving.

Prerequisites

Ensure any of following is met:

1. Apply Auto-RAID to all objects is selected in the  ESA cluster configuration
2. ESA Auto-RAID is enabled in the  datastore default storage policy

 

Environment

VMware vSAN 9.x

Resolution

Monitor vSAN ESA Effective Capacity

• vSAN ESA effective capacity provides 2 portals in vSAN capacity UI, including effective capacity and space efficiency.

Steps:

1. In the vSphere Client, navigate to the cluster.
2. Click the Monitor tab.
3. Under vSAN, click Capacity to view the effective capacity information

 

Effective Capacity

 

Term	Description
Total usable capacity	Usable physical storage space in the datastore, excluding system reservations and RAID redundancy overhead. For more information on ESA Auto-RAID, see What are vSAN Policies
Used capacity	Used physical storage space in the datastore after global deduplication and compression. It also includes the capacity of the system objects such as performance stats objects, native trace objects, file service root objects, iSCSI home objects, data protection namespace objects, FCD namespace objects, and shared user data
Actually written	Actually used capacity. The amount of data physically written in the datastore, excluding system reservations, RAID overhead, and space reserved by thick provisioning
Object reserved	Over reservation for objects created with thick provisioning in the policy. This capacity is not actually used by the objects
Free usable capacity	Remaining usable capacity available in the datastore, excluding all system reservations. Free usable capacity = (total usable capacity - used capacity)

 

Space Efficiency

 

Term	Description
Total provisioned capacity	Sum of the effective provisioning capacity. This excludes RAID overhead for all the namespace objects
Data reduction ratio	Ratio of the original data size to the actual space used after applying compression and vSAN ESA global deduplication
Deduplication ratio	Ratio of the original size of the deduplication-eligible objects to the actual space used after vSAN ESA global deduplication
Compression ratio	Ratio of the original size of the compressible data to the actual space used after compression
Thin provisioning saving ratio	Ratio of the total provisioned capacity to the actual used capacity
Overprovisioning ratio	Measures how much the total provisioned storage exceeds the total usable capacity available in the datastore
Snapshot saving ratio	Measures the data reduction of snapshots. It is the ratio of the original snapshot size that would be consumed if every snapshot was fully inflated to the actual physical capacity currently used by all snapshots
Fully inflated snapshot capacity	Total storage that all snapshots can use at full logical size without data reduction techniques such as local snapshots or vSAN ESA global deduplication
Snapshot used capacity	Total storage used by all snapshots in the cluster including the shared data blocks

• Use the following formula to calculate the total usable capacity:

        Total Usable Capacity = (Total Raw Capacity - System Usage) / RAID Factor

Term	Description
Total Raw Capacity	Total claimed disk volumes on the ESA datastore
System Usage	Includes System Overhead and System Reservation System Overhead includes the following: Global Metadata overhead - The capacity of the performance tier. File system overhead - on-disk format overhead that may take up the capacity drives. ESA objects overhead - ESA uses the capacity to store object metadata and to provide high performance. Deduplication overhead - Overhead to get the benefits of global deduplication in ESA cluster. This data is visible only if you enable vSAN ESA global deduplication. System Reservations is the minimum space required for operations
RAID Factor	Determined based on the cluster configuration. The RAID factor can be 1.5 for a standard cluster with auto managed RAID policy

 

For example, if the total raw capacity is 40 TB, the system overhead (that includes system overhead and system reservations) is 14.5 TB, and the RAID factor is 1.5, the total usable capacity available is 17 TB (40-14.5)/1.5

 

vSAN Max support

• vSAN ESA effective capacity is supported for vSAN Max.
• The compute client cluster displays ESA effective capacity for the remote datastore.
• When you enable effective capacity on the remote  datastore, the compute client cluster displays total usable capacity, used capacity, and free effective capacity.
• If you do not enable the effective capacity, the client cluster displays the legacy capacity usage of the remote datastore that includes total capacity, used capacity, and actually written capacity.

Additional Information