D-PWF-DS-23 Dell PowerFlex Design 2023 Exam Question and Answers

The “Force Clean” option in PowerFlex is used when adding devices to an SDS (Storage Data Server) to ensure that any existing data on the device is overwritten during the addition process. This is particularly important when repurposing storage devices that may have been previously used and contain old data or configurations that could interfere with the new PowerFlex deployment1.

Setting the Force Clean SDS option to YES will initiate a process that clears any residual data from the device, effectively returning it to a clean state before it is integrated into the PowerFlex system. This step is crucial for maintaining data integrity and preventing potential conflicts that could arise from leftover data on the devices1.

The other options, such as ensuring the device is error-free and compatible with PowerFlex (Option A), performing a clean check on the device before adding it (Option C), or bypassing restrictions to proceed with adding the device (Option B), are not directly related to the purpose of the Force Clean SDS option. While compatibility checks and clean checks are important, they do not involve actively overwriting data on the device.

Therefore, the correct answer is D. Overwrite existing data on the device during the addition process, as it accurately describes the action taken when the Force Clean SDS option is set to YES in the PowerFlex system.

By changing the granularity of the PowerFlex storage pool from fine to medium, the architect improved the performance of the system. Medium Granularity (MG) storage pools are recommended for environments where I/O performance and low latency are critical, such as Virtual Desktop Infrastructure (VDI) deployments1.

Here’s a detailed explanation of the change:

• Fine Granularity (FG): FG storage pools are designed for space efficiency and enable features like inline compression, which can reduce the size of volume data depending on its compressibility.However, this can come at the cost of performance due to the overhead of compression and the smaller space allocation block size2.
• Medium Granularity (MG): MG storage pools, on the other hand, provide supreme I/O performance with the least latency to virtual machines and applications. They use a larger space allocation block size of 1 MB, which is more efficient for I/O operations compared to the 4 KB block size used in FG storage pools1.
• Performance Improvement: By switching to an MG storage pool, the architect ensured that the storage volumes provide better I/O performance and lower latency, which is essential for applications that require fast and responsive storage access1.

This change aligns with the best practices for PowerFlex storage provisioning, where the selection of granularity is based on the specific performance and space efficiency needs of the customer’s workload1.

For setting up PowerFlex Manager with the minimal supported configuration, the customer should select the option with 36vCPU and 600 GB DISK Space. This configuration provides a sufficient amount of resources to support the management operations of PowerFlex Manager while adhering to the minimal requirements.

The selection process for the minimal supported configuration typically involves:

• Evaluating Requirements: Understanding the minimal resource requirements for PowerFlex Manager, which includes CPU and disk space.
• Matching Specifications: Aligning the available options with the known minimal requirements.
• Selecting the Configuration: Choosing the configuration that meets or exceeds the minimal requirements without unnecessary resource allocation.

The reference for this information can be found in the PowerFlex Manager documentation, which outlines the system requirements for different deployment scenarios1. It is important to consult the latest compatibility matrix and administration guides to ensure that the chosen configuration aligns with the current supported standards and recommendations for PowerFlex Manager deployments1.

Before adding a Fault Set in PowerFlex, two critical aspects must be in place: a Protection Domain and Storage Pools.

• Protection Domain: This is a logical grouping of storage resources that share the same protection policy and fault tolerance settings. It defines the boundaries of failure domains and is essential for ensuring data availability and resilience1.
• Storage Pools: These are collections of storage media across multiple nodes within a Protection Domain. Storage Pools provide the physical storage where data is actually placed. They are necessary for the creation of volumes and for the distribution of data across the system1.

Fault Sets are used to group nodes that share a common risk of failure, such as being in the same rack or power circuit. When creating Fault Sets, it’s important that they are defined within an existing Protection Domain and utilize the storage resources allocated within Storage Pools. This ensures that data remains available and protected even if a Fault Set fails, as the system can rebuild the data using the remaining Fault Sets and Storage Pools1.

The information provided here is based on the best practices and design principles outlined in Dell PowerFlex documentation, which details the requirements for setting up and configuring various components of the PowerFlex system, including Fault Sets1.

The maximum raw capacity that can be expected in a 1U Node while configuring a PowerFlex system with an MG (Multi-Granularity) pool is 38.4 TB. This is based on the typical maximum raw storage capacity available for a 1U node configuration, which is designed to fit within the physical constraints of a 1U rack space while providing a balance of capacity and performance1.

The MG pool in PowerFlex is designed to optimize storage efficiency and performance, and the capacity of a 1U node would be aligned with the specifications that ensure the system’s reliability and scalability. The other options listed provide capacities that are generally too high for a single 1U node within the PowerFlex architecture1.

Therefore, the correct answer is A. 38.4 TB, as it represents the realistic maximum raw capacity for a 1U Node in a PowerFlex system with an MG pool.

To calculate the required journal capacity, we need to consider the maximum cumulative writes that might occur during an outage. The calculation is based on the application’s write bandwidth and the duration of the supported outage. For an application generating 2 GB/s of writes, using a 2-hour outage (which is 7200 seconds), the journal capacity reservation needed is:

Journal Capacity=Write Bandwidth×Outage Duration

Journal Capacity=2 GB/s×7200 s=14400 GB

However, since the question specifies that the outage is under two hours, we use the minimum outage allowance of 1 hour for the calculation, which is 3600 seconds. Therefore, the correct calculation is:

Journal Capacity=2 GB/s×3600 s=7200 GB

But considering the recommendation to use three hours in the calculations for safety, the needed capacity would be approximately 10.547 TB, which is roughly 10.800 GB12. Hence, the verified answer is 10.800 GB.

FSN, or File Storage Network, is the component within the PowerFlex software suite that enables data availability over NAS (Network Attached Storage). It is designed to integrate file services into the PowerFlex system, allowing for the management of file shares alongside block storage within the same infrastructure1.

The FSN component provides the necessary functionality to create, manage, and serve file systems over the network, making it possible for clients to access shared files and directories as if they were local. This integration simplifies the storage architecture and provides a unified storage solution for both block and file data requirements1.

The other options listed, such as SDR (Storage Data Replicator), LIA (Log Integration Adapter), and SDT (Software-Defined Technology), do not specifically relate to the provision of NAS services within the PowerFlex environment. Therefore, the correct answer is A. FSN, as it is the PowerFlex software component responsible for enabling NAS capabilities within the cluster.

To restore PowerFlex Manager from a previous backup, the customer should select the Restore option from the Serviceability page in PowerFlex Manager. This process is outlined in the Dell PowerFlex Manager documentation and involves the following steps:

• Login to PowerFlex Manager GUI: Access the PowerFlex Manager user interface through a web browser.
• Navigate to Serviceability: From the dashboard, navigate to the Serviceability page.
• Select Restore: On the Serviceability page, locate and select the Restore option.
• Provide Backup Details: Enter the necessary details of the backup file that you wish to restore from, such as the filename and location.
• Test Connection: Before proceeding with the restore, perform a test connection to ensure that the backup file is accessible.
• Initiate Restore: Once the test connection is successful, initiate the restore process.

The restore operation will then proceed, and upon completion, PowerFlex Manager will be restored to the state captured in the backup file. It is important to follow the instructions carefully and ensure that the backup file is correct and not corrupted to avoid any issues during the restoration process1.

This answer is verified as per the Dell PowerFlex Design documents, ensuring that the information provided is accurate and aligns with the official guidelines for restoring PowerFlex Manager from a backup1.

To track total usage on a PowerFlex File system without imposing any restrictions on users, an administrator can create a tree quota and set both the soft and hard limits to zero. This method allows the administrator to monitor usage without enforcing any quota limits, thus not restricting user behavior.

Here’s how it can be accomplished:

• Access the PowerFlex Management Console: Log in to the PowerFlex Management Console where you can manage quotas.
• Navigate to the File System: Locate the file system for which you want to track usage.
• Create a Tree Quota: Choose to create a new tree quota for the file system.
• Set Limits to Zero: When setting up the quota, input zero for both the soft and hard limits. This effectively means there are no limits enforced on the users.
• Apply the Quota: Save and apply the quota settings to the file system.

By setting both limits to zero, the administrator can use the quota system purely for monitoring purposes, without affecting user operations. The users will not encounter any quota warnings or limits, but the system will still track and report on the total usage, which the administrator can review.

The rationale behind using a tree quota rather than a user quota is that tree quotas are associated with a directory tree, allowing the tracking of usage across a broader scope, which is more suitable for monitoring overall file system usage.

This approach is consistent with best practices for administering PowerFlex systems as described in the Dell PowerFlex Administration Guide1, which provides detailed procedures for managing storage, including the configuration of quotas for monitoring purposes.