vSAN storage

Overview

vSan Storage in the Supply Chain

For environments that use hyperconverged infrastructure to provide storage on a vSAN, Turbonomic can discover the storage provided by a host cluster as a single Storage entity. This Storage entity represents the full storage capacity that is provided by that host cluster.

Turbonomic supports VMware vSAN, but does not support stretched VSAN clusters. Adding stretched clusters can cause the generation of incorrect storage recommendations and actions.

vSAN storage capacity

When you consider vSAN capacity, you need to compare Raw Capacity with Usable Capacity.

  • Raw Capacity

    Turbonomic discovers Raw Capacity configured in vCenter and uses it to calculate Usable Capacity. Raw Capacity displays in the Entity Information chart.

  • Usable Capacity

    Turbonomic calculates Usable Capacity and then uses the calculated value to drive scaling actions. Turbonomic can recommend scaling the Storage Amount, Storage Provisioned, or Storage Access capacity. Usable Capacity displays in the Capacity and Usage chart.

Usable capacity calculation

To calculate Usable Capacity, Turbonomic considers a variety of attributes, including:

  • Raw Capacity and Largest Host Capacity

    Turbonomic compares the Raw Capacity for all the hosts in the cluster and then uses the largest value as Largest Host Capacity.

  • RAID Factor

    Turbonomic calculates RAID Factor based on the Failures to Tolerate (FTT) value and Redundancy Method that it discovers. FTT specifies how many failures a given cluster can tolerate, while Redundancy Method specifies the RAID level for the cluster.

    FTT Redundancy method RAID factor
    0 RAID1 1
    1 RAID1 1/2
    2 RAID1 1/3
    1 RAID5/6 3/4
    2 RAID5/6 2/3
    Note:

    If discovery fails for some reason, Turbonomic uses a RAID Factor of 1.

  • Host Capacity Reservation, Slack Space Percentage, and Compression Ratio

    You can control the values for these attributes in storage policies. For details about these attributes and their effect on usable capacity calculations, see Hyper-converged Infrastructure Settings.

The calculation for Usable Capacity can be expressed as:

Usable Capacity = (Raw Capacity - Largest Host Capacity * Host Capacity Reservation) * Slack Space Percentage * RAID Factor * Compression Ratio

If the result of the calculation is zero or a negative value, Turbonomic sets the Usable Capacity to 1 MB.

Capacity and usage chart for vSAN storage

The Capacity and Usage chart for vSAN storage shows two Storage Amounts - Consumed (bought) and Provided (sold). This is because vSAN storage can buy and sell commodities to hosts.

For the Provided Storage Amount, the Capacity value corresponds to Usable Capacity, while the Used value indicates utilization.

Entity information chart for vSAN storage

The Entity Information chart includes the following information:

  • HCI Technology Type

    The technology that supports this storage cluster. For this release, Turbonomic supports VMware vSAN technology.

  • Capacity

    Turbonomic displays rounded values for the following, which might be slightly different from the values it discovers from vCenter:

    • Raw Capacity

      The sum of the Raw Capacity that each storage capacity device provides.

    • Raw Free Space

      How much of the Raw Capacity is not currently in use.

    • Raw Uncommitted Space

      In terms of Raw Capacity, how much space is available according to your thin/thick provisioning.

  • Redundancy Method and Failures to Tolerate

    Redundancy Method specifies the RAID level employed for the cluster. RAID level impacts how much Usable Capacity you can see for a given Raw Capacity. You can use a RAID calculator to determine how the RAID level impacts your Usable Capacity.

    Failures to Tolerate specifies how many capacity device failures a given cluster can tolerate. In practical terms, this means how many hosts can come down at the same time, without affecting storage. This value should match the RAID level.

Actions to add vSAN capacity

To scale up storage amount, you add additional hosts that are configured to include their storage in the vSAN array.

When you scope the session to the vSAN storage, you can see actions to scale:

  • Storage Amount

  • Storage Provisioned

  • Storage Access

The action to scale up the storage indicates the amount of storage you need to add. It appears as a recommended action. In fact, to add storage you must add a new host.

When you scope the session to hosts that provide the capacity devices to the storage, you can see the following actions that are related to scaling up the storage capacity:

  • Scale up StorageAmount for Storage [MyVsanStorageCluster]

  • Provision Host [VSAN_HostName]

The action to provision a host includes details about the storage cluster. Because you need to manually add hosts to your on-prem environment, this appears as a recommended action.

Planning with vSAN storage

For Hardware Replace and Custom plans, you can use HCI Host templates to add vSAN capacity. These represent the hosts that add storage capacity to a vSAN cluster. For more information, see HCI Host Template Settings.

Under certain circumstances, Add Virtual Machines plans can fail to place workloads, or it can fail to generate actions to increase storage capacity by provisioning new hosts.

  • If you scope the plan to a user-created group that only provides vSAN storage, or to a discovered storage cluster group, then the plan can fail to place VMs with multiple volumes. This can occur for VMs that use conventional storage (not vSAN) along with vSAN storage.

  • If you scope the plan to a vSAN host group and add VMs, the plan can fail to increase storage capacity by provisioning new hosts. For example, assume you scope the plan to a vSAN host group and add 20 VMs to the environment. In that case, you need hosts to provide compute capacity for the VMs, and you also need hosts to provide storage capacity. The plan can represent the compute provisioning correctly, but it can incorrectly fail to add more storage capacity to the vSAN.

  • If the vSAN RAID type is Raid6/FTT=2, if you scope the plan to any vSAN groups then the plan will fail to place any of the VMs.