This feature is applicable in scenarios where it is essential to have small I/O operations on a specific set of Azure Managed Disks, making it particularly beneficial for SAP HANA workloads. Before we dive into configuring the Write Accelerator, it’s crucial to understand the eligibility requirements.
Eligibility Requirement for Write Accelerator
- Availability – The VM should be in a region where the Write Accelerator is available.
- VM series – Only specific types of Azure VM series are eligible for WA.
- Disk Type – Premium SSDs or Ultra Disks.
- Disk Size – Minimum disk size required is 1 TiB.
- VM Operation – The Write Accelerator feature can only be enabled when the relevant VM is in the stopped (deallocated) state.
Configuring the Write Accelerator
To realize the best return on investment, it’s key to configure the Write Accelerator correctly. For instance, Write Accelerator can be enabled for both new and existing disks associated with a particular VM.
For clarity, the example below outlines the steps to enable Write Accelerator for Azure Managed Disks using Azure PowerShell:
#Provide the subscription Id
$subscriptionId = “yourSubscriptionId”
#Name of your resource group
$resourceGroupName = “yourResourceGroupName”
#Name of the VM on which you want to enable Write Accelerator
$vmName = “yourVMname”
#Name of the disk for which you want to enable Write Accelerator
$diskName = “yourDiskname”
Select-AzureRmSubscription -SubscriptionId $subscriptionId
$vm = Get-AzureRmVM -ResourceGroupName $resourceGroupName -Name $vmName
$vm.StorageProfile.DataDisks[0].CreateOption = “Attach”
$vm.StorageProfile.DataDisks[0].ManagedDisk.Id = $diskId
$vm.StorageProfile.DataDisks[0].WriteAcceleratorEnabled = $true
Update-AzureRmVM -ResourceGroupName $resourceGroupName -VM $vm
In the snippet above, ensure to replace the placeholders with your actual subscription ID, resource group name, VM name, and disk name.
Benefits and Limitations
Like any other feature, the Azure Write Accelerator feature does have benefits as well as limitations.
| Benefits | Limitations |
|---|---|
| 1. Greatly improves the performance of write-intensive and log-based transactions. | 1. Only relevant for Azure M-Series and selected DS_v3 or ES_v3 VMs. |
| 2. The ability to enable and disable the WA on-demand without requiring disk detach or data migration. | 2. Only works with Premium SSD or Ultra Disks and their minimum size should be 1 TiB. |
| 3. Minimal impact on the Azure VM or Disk SKU Pricing. | 3. Limited support to specific regions. |
In conclusion, WA is a feature that harnesses small write I/O intensity scenarios for SAP workload in Azure. It’s always necessary to indulge in a careful assessment before enabling WA as it might cause VM unavailability during the process. When successfully implemented, Write Accelerator can provide a significant boost to the performance of your SAP workloads on Azure.
Practice Test
True or False: Azure Write Accelerator is available only with Azure Premium SSD disks.
- True
- False
Answer: True
Explanation: Write Accelerator is a feature on Azure specifically designed for Azure M-series virtual machines (VMs) and only available with Azure Premium SSD managed disks.
True or False: Write Accelerator is designed to reduce write latency for data files, log files, and disk configurations.
- True
- False
Answer: True
Explanation: Write Accelerator is designed to deliver sub-millisecond write latency for your most write-intensive workloads including databases’ log file write.
What kind of Azure services can use Write Accelerator?
- A. Azure Premium SSD
- B. Azure Ultra Disk SSD
- C. Azure Blob Storage
- D. Azure Files
Answer: A. Azure Premium SSD
Explanation: Write Accelerator is a feature designed to work with Azure Premium SSD managed disks and currently not available for other storage services.
True or False: Write Accelerator cannot help in increasing write-intensive workload.
- True
- False
Answer: False
Explanation: Write Accelerator is designed to lower the write latency for log write scenarios and can significantly increase performance for write-intensive workloads.
Which of the following virtual machine series supports Write Accelerator?
- A. M-series
- B. Ls-series
- C. A-series
- D. B-series
Answer: A. M-series
Explanation: M-series virtual machines currently support Write Accelerator.
For enabling write accelerator on a disk, the disk must be _____
- A. Attached to an M-series VM
- B. In a virtual network
- C. In the same region as VM
- D. All of the above
Answer: D. All of the above
Explanation: Write Accelerator can be enabled on a disk attached to M-series VM and the VM and disk should be in the same region.
True or False: Write Accelerator, once enabled, can be disabled without any disruptions.
- True
- False
Answer: False
Explanation: Disabling Write Accelerator requires you to stop/deallocate the associated VM, hence it can cause disruptions.
True or False: Write Accelerator is recommended for all disk types.
- True
- False
Answer: False
Explanation: Write Accelerator is specifically designed for operating with Azure Premium SSD managed disks.
Which of the following workloads does Write Accelerator benefit the most?
- A. Read-Intensive workloads
- B. Write-Intensive workloads
Answer: B. Write-Intensive workloads
Explanation: Write Accelerator are designed to lower the write latency, hence benefiting write-intensive workloads the most.
True or False: You can enable Write Accelerator for both OS disk and data disks in the virtual machine.
- True
- False
Answer: False
Explanation: Write Accelerator can only be enabled on data disks and is not supported for OS disks.
Interview Questions
What is the primary purpose of Azure Write Accelerator?
Azure Write Accelerator is designed to improve write latency performance of Azure Managed Disks and Azure VMs.
In which Azure Disk Storage Type is Azure Write Accelerator available?
Azure Write Accelerator is available in Premium SSD.
Which Operating Systems support Azure Write Accelerator?
Azure Write Accelerator supports Windows and Linux operating systems.
How can Azure Write Accelerator be enabled or disabled?
Azure Write Accelerator can be enabled or disabled through the Azure portal, PowerShell, Azure CLI, or directly through the REST API.
What is the maximum I/O size supported by Azure Write Accelerator?
Azure Write Accelerator supports a maximum I/O size of 1 MB.
Are any SAP applications officially supported on Azure instances using Write Accelerator?
Yes, Write Accelerator can be used with the SAP HANA database, as long as the database’s redo logs are placed on the disks that have Write Accelerator enabled.
When using Azure Write Accelerator, what is the ideal target for reducing write latency?
The ideal target for reducing write latency when using Azure Write Accelerator is High Performance and Mission Critical transactional workloads like SAP HANA.
Is there any impact on the storage size of managed disks when enabling the Write Accelerator?
No, enabling or disabling the Write Accelerator does not have any impact on the storage size of managed disks.
What is the main advantage of using Azure Write Accelerator for SAP HANA?
By using Azure Write Accelerator for SAP HANA, you can achieve write latency of less than 1ms, ensuring that database transactions are committed quickly and consistently.
Can Azure Write Accelerator be enabled for Standard SSD or Standard HDD?
No, Azure Write Accelerator can only be enabled for Azure Managed Disks in Premium SSD.
Must an Azure VM be stopped before enabling or disabling the Write Accelerator feature?
Yes, the Azure Virtual Machine must be in a stopped(deallocated) state to enable or disable Azure Write Accelerator.
Can Write Accelerator be used with Ultra SSD?
No, as per current Azure services, the Write Accelerator feature is not available with Ultra SSD.
How does Azure Write Accelerator benefit transactional workloads?
Azure Write Accelerator provides low-latency writes for transaction-heavy workloads, reducing the time taken for individual transactions and making the system more efficient.
Can Azure Write Accelerator be applied retroactively to an existing Premium SSD Managed Disk?
Yes, but the VM will need to be stopped and deallocated before enabling the Write Accelerator on the associated disk.
Is Azure Write Accelerator available in all Azure regions?
No, Azure Write Accelerator availability may vary by region.
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