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vSphere migration is one of the fundamental features that enables VMs to move between compute or storage locations. Migration allows workloads to be reallocated to different hardware for load balancing, hardware, or hypervisor upgrades. vSphere migration can be performed in two basic ways:
While vSphere vMotion technology allows VMs to run uninterrupted, there are several considerations to enable vMotion functionality. Design and configuration of the vSphere environment, including compute, storage, and network, all need to be done properly with vMotion in mind. Although VMs run uninterrupted during vMotion migrations, the migration time and workload performance impact will vary depending on the environment. The environment needs to be designed to support the required migration times and performance requirements during vMotion activities.
During a vMotion, either compute, storage or both can be migrated. Typically, storage migrations are the most challenging due to the storage size. Because applications such as SQL Server can have a large storage footprint and demanding performance requirements, it is beneficial to avoid a storage migration. In environments with larger SQL Server instances, vMotion was often not a viable option due to storage size or performance requirements.
Dell PowerStore has deep integration with vSphere and supports many vSphere storage features that can help to avoid storage migrations. One of those key features is PowerStore support for SCSI-3 Persistent Reservations (PR) that allow multiple nodes to access the same PowerStore storage device. SCSI-3 PR allows PowerStore appliances in a cluster to present block volume or virtual volume (vVol) resources to multiple VMware ESXi hosts. Therefore, when a vMotion is required between hosts, the storage migration is not necessary. The VMware vVol or Virtual Machine File System (VMFS) datastore is already visible to the other host, allowing for a more efficient compute only vMotion. Compute only vMotion provides a faster vMotion experience with minimal performance impact.
Eliminating a storage vMotion for a SQL Server VM can enable vMotion as a HA option where it was not possible otherwise. vMotion provides a powerful and simple option for increasing SQL Server availability without the complexity of adding additional HA features.
Adding a second PowerStore cluster can increase redundancy at a local site or provide multisite availability. The PowerStore Metro volume feature allows VMFS datastores to be synchronously replicated to a second PowerStore cluster for load balancing and increased availability. By adding a PowerStore Metro witness to the Metro volume configuration, automatic failover can be often achieved. In this configuration, SQL Server VMs can run uninterrupted through a storage appliance or network failure and can vMotion between data centers or physical sites with a compute only migration. Metro volume is a powerful feature to enhance SQL Server availability and enable additional vMotion SQL Server use cases.