Storage vMotion for production Oracle RAC workloads to new or different storage array

Products

• VMware vCenter Server

Issue/Introduction

The article explains the considerations and steps to perform a storage vMotion for production Oracle RAC workloads to new or different storage array

 

Environment

VMware vSphere ESXi 7.0 U3x

VMware vSphere ESXi 8.0 x

Resolution

Key points to remember:

Multi-writer attribute:
This setting on a shared VMDK allows multiple VMs to write to the same disk simultaneously, which is essential for an Oracle RAC cluster where all nodes need to access shared data. 
 
Storage vMotion:
This VMware feature is used to migrate virtual machine disks to a different datastore without impacting running VMs. 

 
Migration steps:

1. Prepare the cluster:
Backup data!: Ensure you have a recent backup of the RAC database before starting the migration process. 
 
Disable HA: Temporarily disable High Availability (HA) on the RAC VMs to avoid automatic restarts during the migration. 
 
2. Isolate shared disks:
Remove multi-writer flag: On all but one of the RAC VMs, remove the multi-writer attribute from the shared VMDKs. 
 
3. Migrate VMs one by one:
Storage vMotion: Use Storage vMotion to migrate the first RAC VM (with the multi-writer flag on shared disks) to the new datastore. 
 
Repeat for other VMs: Repeat the Storage vMotion process for each remaining RAC VM, migrating them to the new datastore, ensuring each VM is migrated individually. 
 
4. Re-apply multi-writer flag:
Add multi-writer attribute: Once all VMs are on the new datastore, re-apply the multi-writer attribute to the shared VMDKs on all VMs. 
 
5. Verify and re-enable HA:
Cluster verification: Check the RAC cluster functionality on the new datastore to ensure all nodes are properly communicating and accessing shared data. 
 
Re-enable HA: Re-enable High Availability on the RAC VMs. 
 

Important considerations:

Downtime:
Migrating an Oracle RAC cluster with shared disks typically involves some downtime as you need to temporarily disable the multi-writer attribute on the shared disks. 
 
Cluster management:
Always coordinate the migration process with your cluster management tools to ensure consistency across all RAC nodes. 
 Best Practices:

1. Backup Data: Ensure you have a complete backup of all data before starting the migration.
2. Check Compatibility: Verify that the target datastore supports multi-writer VMDKs.
3. Resource Allocation: Ensure sufficient CPU, memory, and storage resources are available on the target hosts.
4. Test Environment: Perform a dry run in a test environment to identify and resolve any potential issues.
5. Verify Post-Migration: After the migration, verify that the Oracle RAC Cluster is functioning correctly and that all data is accessible.

Additional Information

Reference: 

Storage vMotion for Production Oracle RAC Workloads with NO downtime – Same vSphere Cluster , Different Storage Array
https://blogs.vmware.com/apps/2018/03/around-storage-world-no-time-storage-vmotion-oracle-workloads.html