Dell Storage Manager 2020 R1 Administrator's Guide

Data Reduction Options for VVols

You can specify data reduction options when creating storage containers. These options are advertised (made available) to the VMware administrator during VM Storage Profile creation.

When you use Dell Storage Manager to create storage containers, you can optionally set these data reduction options:

Deduplication Allowed
Compression Allowed

Specifying one or both of these options indicates the data reduction preferences for VMs that are then created.

You can also specify options for Data Reduction Input:

None
Compression
Deduplication with Compression

These options are presented as checkboxes on the Create Storage Container wizard.

NOTE:Even if the Compression Allowed and Deduplication Allowed checkboxes are selected, selecting the None profile option results in no action being taken.

You can also select the Default Data Reduction Profile, if one has been specified using the User Preferences.

After a storage administrator creates a storage container with data reduction options specified, these options are advertised (shown as being selected) on the VM Storage Profile wizard when a VMware administrator creates a storage profile. If you edit the storage container’s Data Reduction option, you also change the advertised capabilities that are visible in the VM Storage Profile.

For information about using VM Storage Profiles, see the VMware vCenter documentation.

Factors That Affect Data Reduction Operation

When a new virtual volume is created, it can use any Data Reduction type supported by the storage container. The preference for the Data Reduction type on the virtual volume is influenced by either:

The VM Storage Profile, if one is established and used
The default Data Reduction Profile set for the storage center

The following factors affect how Data Reduction options are applied:

If no VM Storage Policy is chosen, the Data Reduction type defaults to the value selected by the Default Data Reduction Profile.
Editing an existing storage container’s properties to change the value of the Default Data Reduction Profile does not affect existing virtual volumes. This change applies only to new volumes created afterward.
If an existing volume has an enabled feature that is now disabled, the volume itself does not change. In the VM Storage Profile, the volume would now appear to be noncompliant. To bring the volume back into compliance, you can apply a compliant policy to the volume.

NOTE:The VM Storage Profile takes precedence when compatible storage exists.

NOTE:VM storage policies are applied only to data and config VVols and not to memory and swap VVols.

NOTE:When modifying VM storage policies especially for compression and deduplication, apply the VMware administrator policies to all volumes associated with VM. If these same changes are not applied to all volumes, some portion of the VM could be compressed while other portions could be uncompressed.

NOTE: The advertised capabilities only apply to VVols datastores and are not supported on legacy VMFS datastores.

NOTE:Any change to a storage container's Data Reduction profile might cause future fast cloned VMs to be created with mismatched Data Reduction profiles for the config and data VVols. A fast clone VM shares history with the VM from which it was created. Hence its data VVols inherit the settings of the data VVols of the original VM. There is another side effect of this shared history — if a user applies a VM Storage Policy to the original VM, the same changes apply to the data VVols of the fast clone VM and conversely.

NOTE:When applying a VM Storage Policy containing rules for the ScStorageProfile capability, the vCenter administrator can ignore the datastore compatibility warning Datastore does not satisfy required properties.. The VASA provider overrides the datastore's configured value and applies the user-provided value of ScStorageProfile for VVols of the VM.

Expected Behaviors for Data Reduction Scenarios

The settings specified in both the storage container Data Reduction options and in the VMware Storage Profile determine the results of VM and VVol creation. If the storage container Data Reduction settings conflict with the settings in the VM Storage Profile, creation of VMs and virtual volumes could fail.

The following table describes the expected behavior for new VM creation with the Compression option.

Table 1. Expected Behavior for New VM Creation with Compression
	VM Storage Policy = None Specified	VM Storage Policy = Compression Enabled	VM Storage Policy = Compression Disabled
Storage Container Compression Enabled	Volumes created with Default Data Reduction profile value from storage container	Volumes created with Compression Data Reduction Profile	Volumes created with the Data Reduction Profile set to None
Storage Container Compression Disabled	Volumes created with Default Data Reduction profile value from storage container	VM creation fails because user is trying to set an unsupported capability	Volumes created with the Data Reduction Profile set to None

The following table describes the expected behavior for new VM creation with the Deduplication option.

Table 2. Expected Behavior for New VM Creation with Deduplication
	VM Storage Policy = None Specified	VM Storage Policy = Deduplication Enabled	VM Storage Policy = Deduplication Disabled
Storage Container Deduplication Enabled	Volumes created with Default Data Reduction profile value from storage container	Volumes created with Dedup with Compression Data Reduction Profile	Volumes created with the Data Reduction Profile set to None
Storage Container Deduplication Disabled	Volumes created with Default Data Reduction profile value from storage container	VM creation fails because user is trying to set an unsupported capability	Volumes created with the Data Reduction Profile set to None

The following table describes the expected behavior for existing VMs when a vCenter user changes the associated VM policy. This table assumes that both Compression and Deduplication are enabled on the storage container.

Table 3. Expected Behavior for VM Storage Policy Update on Existing VMs
Old VM Storage Policy	New VM Storage Policy	Expected Behavior
Compression Enabled	Compression Disabled	Data Reduction Profile of associated VVols changes from Compression to None. Data is uncompressed at the next data progression cycle.
Compression Disabled/None Specified	Compression Enabled	Data Reduction Profile of associated VVols changes from None to Compression. Data is compressed at the next data progression cycle.
Deduplication Disabled	Deduplication Enabled	Data Reduction Profile of associated VVols changes to Deduplication with Compression. Data is deduplicated at the next data progression cycle.
Deduplication Enabled	Deduplication Disabled	Data Reduction Profile of associated VVols changes from Deduplication with Compression to None. Data is rehydrated at the next data progression cycle.

The following table describes the expected behavior for existing VMs when a storage administrator selects or clears the Compression and Deduplication checkboxes on a storage container.

Table 4. Expected Behavior for Compression and Deduplication Checkboxes on Storage Container
Old Checkbox Value	New Checkbox Value	Expected Behavior
Compression Enabled	Compression Disabled	Data Reduction Profile of existing volumes remains unchanged. Compliance check warns that the VM is not compliant with storage container. Clone/Fast Clone of VM to the same storage container follows rules of Table 1 and might fail if the VM Storage Policy is now noncompliant. New volumes are created with the Data Reduction Profile set to None.
Compression Disabled	Compression Enabled	Data Reduction Profile of existing volumes remains unchanged. Clone/Fast Clone of VM to the same storage container follows rules of Table 1 and does not fail. New volumes are created with the Data Reduction Profile according to Table 1.
Deduplication Disabled	Deduplication Enabled	Data Reduction Profile of existing volumes remains unchanged. Clone/Fast Clone of VM to the same storage container follows rules of Table 2 and does not fail. New volumes are created with the Data Reduction Profile according to Table 2.
Deduplication Enabled	Deduplication Disabled	Data Reduction Profile of existing VVols remains unchanged. Compliance check warns that the VM is not compliant with the storage container. Clone/Fast Clone of VM to the same storage container follows rules of Table 2 and might fail if the VM Storage Policy is now noncompliant. New volumes are created with the Data Reduction Profile based on Table 1 if Compression is enabled or with the Data Reduction Profile set to None.

The following table describes the expected behavior for datastores related to migration.

Table 5. Expected Behavior Related to Migration
Source Datastore	Destination Datastore	Expected Behavior
Storage Container Deduplication = Supported	Storage Container Deduplication = Supported Destination VM Storage Policy = Deduplication Enabled	Migration succeeds. The volume on the destination is created with the Deduplication with Compression Data Reduction Profile.
Storage Container Deduplication = Supported	Storage Container Deduplication = Not Supported Destination VM Storage Policy = Deduplication Enabled	Migration fails because the source VM Storage Policy is invalid on the destination.
Storage Container Deduplication = Supported Default Data Reduction Policy on Container = Deduplication with Compression	Storage Container Deduplication = Not Supported Destination VM Storage Policy = None Specified	Migration succeeds. The volumes on the destination inherit the destination storage container's default Data Reduction Profile.
Storage Container Compression = Supported	Storage Container Compression = Not Supported VM Storage Policy = Compression Enabled	Migration fails because the source VM Storage Policy is invalid on the destination.
Storage Container Compression = Supported Default Data Reduction Policy on Container = Compression	Storage Container Compression = Not Supported VM Storage Policy = None Specified	Migration succeeds. The volumes on the destination inherit the destination storage container's default Data Reduction Profile.

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Dell Storage Manager 2020 R1 Administrator's Guide

Data Reduction Options for VVols

Factors That Affect Data Reduction Operation

Expected Behaviors for Data Reduction Scenarios

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