What Is PowerStore – Part 7, Importing External Storage
So far, we have covered the following aspects of Dell EMC PowerStore:
PowerStore has a native migration capability that is known as Orchestrator, which can be used to import storage resources from Dell EMC storage systems non-disruptively. This capability is integrated in the PowerStore system without the need of any external appliance; however it does requires installing a host plug-in for a non-disruptive import to PowerStore. The host plug-in enables the Orchestrator to communicate with the host multipath software to perform import operations. The combination of native functionality with the host plug-in automates many manual operations that take place during migration. For example, the system automatically completes mapping the hosts, creating the storage resources, and checking the validation.
Supported source block-only storage resources include the following:
• Thick and Thin Clones
• Consistency groups
• VMFS datastores (PS Series only)
• Windows RDM (PS Series only)
Importing file resources using the native-migration capability is not supported.
Supported source systems include the following:
• Dell EMC VNX2
• Dell EMC Unity™
• PS Series (EqualLogic)
• SC Series (Dell™ Compellent™)
For the details about supported storage resources, source systems, and system versions, see the document
Importing External Storage to PowerStore Guide on the PowerStore Info Hub.
The following requirements must be met before migrating to PowerStore:
• The source system must be in a good state and is not running a software upgrade.
• Software or operating environment (OE) version for the source system must be supported.
o See the document Importing External Storage to PowerStore Guide.
o A software upgrade may be required before starting the import.
• Front-end connectivity:
o Connectivity between the client and source system, and the client and PowerStore can be either iSCSI or Fibre Channel (FC).
o For FC, zoning may be required.
o The protocols must match between the source and destination
o iSCSI is used for the data transfer between the source storage system and PowerStore.
o No support for Fibre Channel (FC) for the data transfer between the source and PowerStore system
• A host plug-in must be installed in the clients that access the data to be migrated. Reboot may be required for which reason; it is recommended to do the installation in conjunction to any required software upgrade of the operating system of the client.
Step 1: Setup
The following are the actions that the user should perform before trying to import any storage resources:
1. Configure zoning for the front-end connectivity between the client and the PowerStore system (if required).
2. Add iSCSI connectivity between the source system and PowerStore system (If not available already).
3. Install the host plug-in in each of the clients that requires access to the data during the import. This way ensures that the import is non-disruptive. A reboot may be required as part of the installation of the host plug-in. PowerStore supports three types of host operating systems for the host plug-in:
Linux, Windows, and VMware.
Step 2: Import
The following are the actions that make up the import step:
1. The user adds the source system to the PowerStore Manager
2. Select the added source system and click the Import Storage button, which gives the following options:
a. Select Volumes: Allows selecting the source resources, either as volumes or volume groups, to be imported.
b. Add to Volume Group: Allows the user to group the source resources into an existing volume group or to a new volume group.
c. Add Host: Allows adding the clients in which the user has already configured the host plug-in.
d. Verify Host Mapping: Verifies the host mapping between the selected source resources and the added hosts.
e. Set Import Schedule: Allows setting when will the import begin, either immediately or at a set date and time and with the option to set an automatic cutover is option.
f. Assign Protection Policy: Allows setting an existing protection policy to the selected source resources and applies it once the import completes.
g. Begin Import: The last step of the wizard that shows a summary of the selected options, gives the option to review the source array assigned policies, and shows the Begin Import button to start or schedule the import.
3. Once the Begin Import button is clicked, the following actions are taken by the system.
a. An import session is created.
b. The system request to the host plug-in a path flip, making the paths from the client to the source
system as inactive and activates the paths from the client to the PowerStore system.
c. A background copy of the data from the source system to the PowerStore system starts. Any new writes are made to PowerStore and are forwarded to the source system to ensure rollback.
Step 3: Cutover
1. A cutover is allowed once the import session is in a Ready to Cutover state (the source system and PowerStore are synchronized).
a. The paths from the client to the source system are removed
b. The background copy and the forwarding of writes stops.
c. Once the systems cut over, there is no rollback.
The Internal Migration option from the PowerStore Manager can be used prior to removing or shutting down an appliance for service. This feature is used to move volumes or volume groups to another appliance in the cluster without any disruption. When you migrate a volume or volume group, all associated snapshots and thin clones also migrate with the storage resource. During the migration, additional work space is allocated on the source appliance to facilitate data movement. The amount of space that is needed depends on the number of storage objects and amount of data being migrated. This work space is released and freed up after the migration finishes.
You can either manually migrate storage resources or use the recommendations in PowerStore Manager:
- Manual migration – You can choose to provision a volume or a volume group on a specific appliance or have it automatically get provisioned on an appliance. You can choose to migrate the storage resources to another appliance in the cluster later.
- Assisted migration – In the background, the system periodically monitors storage resource utilization across the appliances. Migration recommendations are based on factors such as drive wear, appliance capacity, and health. If you accept a migration recommendation, a migration session gets automatically created. Migrating resources may require a rescan of all host adapters. I applicable, before you begin the migration, a prompt to acknowledge rescan will appear and list the hosts that require a storage rescan.
Note: migration always requires user action. In no case do storage resources migrate automatically.
You may choose to manually migrate a volume to balance resources across appliances.
In the example, Vol_1 is checked. The volume resides on TwoApplianceCluster-appliance-1. Select the Migrate option to start the task.
The Migrate Volume window appears and provides the user with some useful information about the migration. The example shows TwoApplianceCluster-appliance-2 has been checked and is the destination appliance. Select Start Migration to begin the task.
The Rescan Hosts window gives you a chance to rescan the host to ensure the storage being migrated is still accessible after the migration completes. To rescan the host, use the Rescan Disks option from the Computer Management window, then check the box for Yes, the associated hosts have been rescanned. Once the box is selected, the Start Migration button is available to select.
After starting the migration, you are presented with a message stating that system performance may be impacted for several minutes during the migration. Select the Migrate Now button to begin the migration. View the migration status from the Internal Migration > Migration page.
Once the migration process starts, monitor the progress by viewing the Status columns under the migrations window. Look for a Completed status indicating the resource has been migrated.
The migration process goes though several states the first of which is synchroninzing. During this phase, the majority of the background copy is completed and there are no interruptions to any services. Sync can be run multiple times to reduce the amount of data that must be copied during the cutover.
The cutover phase is the final phase of the migration, when ownership of the volume or volume group is transferred to the new appliance. Active I/O is supported during the migration, however as a best practice, stop I/O to the volume being migrated. Migration is asynchronous until the cutover occurs and can be paused or cancelled anytime during the migration. Before cutover all volumes are fully synchronized.
You can manually move a storage resource. However, the PowerStore GUI can also help with this process. In the example, there are two appliances, PS-2 and PS-3. PS-2 is nearing full capacity and is forecast to run out of space in eight days. A Major Alert is generated. PS-3 still has plenty of space available. Selecting the Alert launches the Alert page.
Selecting the Assisted Migration option from the Repair Flow section returns a list of volumes recommended for migration. The process chooses volumes that impact performance and workloads the least. For example any unmapped volumes or volumes that are mapped but are offline (in MS Disk Manager) or unmounted (Linux) from the host perspective. The recommendations are refreshed every 24 hours. Note the message to warn you that rescan of all HBAs may be required prior to the migration.
There may be a situation where after the migration, there are still capacity issues. In this case, manually migrate the storage resource to solve the issue.
To view the results of the the migration, look at the capacities of the appliances. The PS-2 appliance still displays a capacity over the optimal 80 percent. In this case, further manual remediation may be required.
Once a migration is started, Vol_3 displays a blue dot telling the user a migration job is in progress on the volume.
Once the job starts, monitor the progress by navigating to the Migration > Internal Migrations > Migrations tab to display the status. Selecting the Jobs icon also displays the status of the migration.
The Delete and Pause buttons are available when the migration job starts. Select the migration session and click on the appropriate button. Both options are available while the job is in progress up to the point where the migration displays the Cutting Over status.
Below you can see a demo, showing how to import external volumes to PowerStore
you can also download the white paper by clicking the screenshot below