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Storage DRS and Storage vMotion on datastores managed by VMware vCenter Site Recovery Manager are supported. There are some rules. Storage vMotion or SDRS movements must be limited to devices within a single consistency group. Therefore, for things like datastore clusters, it is required to have only devices in the same consistency group in the cluster. VMware will not allow SDRS to violate these rules and permits greater flexibility with SDRS. Consult VMware SRM documentation for further information.
When Dell FAST (service levels) is used in conjunction with SDRS, only capacity-based SDRS is recommended and not storage IO load balancing. When creating a cluster, simply uncheck the box labeled “Enable IO metric for SDRS recommendations” as in Figure 142 or after creation by editing it as seen in Figure 143. Unchecking this box will ensure that only capacity-based SDRS is in use.
Figure 42. Disabling performance-based SDRS during creation
Figure 43. Disabling performance-based SDRS after creation
Because FAST is actively managing the data on disks to achieve the desired service level, knowing the performance requirements of a VM (on a datastore under FAST control) is important before a VM is migrated from one datastore to another.
Therefore, if the VM contains performance sensitive applications, Dell advises not using SDRS with FAST for that VM. Preventing movement could be accomplished by setting up a rule or at the very least using Manual Mode (no automation) for SDRS.
Note: As all devices are under FAST control on the PowerMax, only capacity-based SDRS is recommended and not storage IO load balancing with that platform.
It is important to take note when Host I/O Limits are set on storage groups that contain devices that are part of a datastore cluster using SDRS. When SDRS is utilized, all devices that are in that datastore cluster should have the same Host I/O Limit. Moreover, the devices should come from the same PowerMax. This recommendation is given because the Host I/O Limit throttles IO to those devices. This may be done to limit the ability of applications on those devices from impacting other devices on the array or perhaps to simplify QoS management. Whatever the reason, if a datastore cluster contains devices - whether from the same or a different array - that do not have a Host I/O limit, there is always the possibility in the course of its balancing that SDRS will relocate virtual machines on those limited devices to non-limited devices. Such a change might alter the desired QoS or permit the applications on the virtual machines to exceed the desired throughput. It is therefore prudent to have device homogeneity when using Host I/O Limits in conjunction with SDRS.