Best Practices for Running SQL Servers on VMware:

1. Proper Resource Allocation: Allocate sufficient CPU, memory, and storage resources to the SQL Server VMs to ensure optimal performance and avoid resource contention.
2. Storage Performance: Use fast and low-latency storage systems for SQL Server VMs, and consider using vSphere features like VMware vSAN or Virtual Volumes (vVols) for better storage management.
3. vCPU Sizing: Size the vCPUs appropriately for SQL Server VMs. Avoid overcommitting CPU resources, and use multiple vCPU cores per socket for better performance.
4. Memory Reservations: Set memory reservations for critical SQL Server VMs to ensure they have guaranteed access to the required memory.
5. VMware Tools and VM Hardware Version: Keep VMware Tools up to date on SQL Server VMs and use the latest VM hardware version supported by your vSphere environment.
6. SQL Server Configuration: Configure SQL Server settings like max memory, parallelism, and tempdb appropriately to match the VM’s resources.
7. vMotion Considerations: Use vMotion carefully for SQL Server VMs to avoid performance impact during migration. Consider using CPU affinity and NUMA settings for large VMs.
8. Snapshots: Avoid using snapshots for long-term backups of SQL Server VMs, as they can lead to performance issues and disk space problems.
9. Monitoring and Performance Tuning: Use vSphere performance monitoring tools and SQL Server performance counters to identify and resolve performance bottlenecks.
10. Backup and Disaster Recovery: Implement a robust backup strategy for SQL Server databases, including both VM-level and database-level backups.
11. High Availability: Use SQL Server AlwaysOn Availability Groups or other clustering technologies for high availability and disaster recovery.
12. Security: Follow VMware security best practices and keep both the vSphere environment and SQL Server VMs patched and updated.
13. Network Configuration: Optimize network settings for SQL Server VMs, including network adapter type and network configurations.
14. Virtual Hardware Assist: Enable virtual hardware assist features like Virtualization-based security (VBS) and Virtual Machine Encryption for better security.
15. Database Maintenance: Regularly perform database maintenance tasks like index rebuilds and statistics updates to keep the SQL Server performance optimal.

PowerShell Script to Backup SQL Server Database:

To back up a SQL Server database using PowerShell, you can use the SQL Server PowerShell module. Below is a sample script to perform a full database backup:

# Load SQL Server PowerShell Module
Import-Module SQLPS -DisableNameChecking

# SQL Server Connection Parameters
$SqlServer = "Your_SQL_Server_Instance"
$DatabaseName = "Your_Database_Name"
$BackupPath = "C:\Backup\"

# Set Backup File Name with Timestamp
$BackupFileName = "$DatabaseName" + "_" + (Get-Date -Format "yyyyMMdd_HHmmss") + ".bak"

# Create Backup SMO Object
$smo = New-Object ('Microsoft.SqlServer.Management.Smo.Server') $SqlServer

# Select Database
$database = $smo.Databases[$DatabaseName]

# Create Backup Device
$backupDevice = New-Object ('Microsoft.SqlServer.Management.Smo.BackupDeviceItem') ($BackupPath + $BackupFileName, 'File')

# Create Backup
$backup = New-Object ('Microsoft.SqlServer.Management.Smo.Backup')
$backup.Action = 'Database'
$backup.Database = $DatabaseName
$backup.Devices.Add($backupDevice)
$backup.SqlBackup($smo)

Write-Host "Backup of database '$DatabaseName' completed successfully."

Replace the placeholders in the script with your actual SQL Server instance name, database name, and the desired backup path. The script connects to the SQL Server instance, creates a backup device, and performs a full database backup using SQL Server Management Objects (SMO).

Ensure that you have the necessary permissions to back up the database on the SQL Server instance and have the required disk space available for the backup. Additionally, consider implementing a comprehensive backup strategy that includes full, differential, and transaction log backups for better data protection and recovery options.