D-MSS-DS-23 Dell Midrange Storage Solutions Design 2023 Questions and Answers

ForNAS (Network Attached Storage)connectivity in Dell Unity XT systems,network availability and redundancyare critical. Dell Unity XT’s best practice for providing thehighest network availabilityfor NAS involvescombining Link Aggregation Control Protocol (LACP) with Fail-Safe Networking (FSN).

✅Why Combine LACP and FSN?

LACP (Link Aggregation Control Protocol)allows multiple physical network links to be combined into a single logical link. This increases bandwidth and provides redundancy at the link level.

FSN (Fail-Safe Networking)provides redundancy at the network path level. It allows two network paths (or groups of links) to be configured with one active and one standby group. If the active path fails, FSN automatically switches to the standby path.

✅Best Practice Benefits:

LACP:Improves link utilization and provides protection against link-level failures.

FSN:Protects against broader network path failures, including switch failures or upstream connectivity issues.

Combined Approach:Providesboth link-level and path-level redundancy, ensuring the highest availability and resiliency for NAS workloads.

✅Documentation Reference:

Dell EMC Unity XT Best Practices Guide (Dell Technologies)– Specifically outlines the recommendation tocombine LACP and FSNfor NAS deployments.

Dell EMC Unity XT Networking Guide– Provides configuration examples and detailed explanations for implementing LACP and FSN in a Unity XT NAS environment.

✅Why not the other options?

A. LACP alone– Improves availability at the link level but not for upstream switch or path-level failures.

B. FSN alone– Provides path-level redundancy but lacks link-level load balancing.

D. Multi-pathing software like PowerPath– Primarily used forblock storage (FC/iSCSI), not NAS.

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Sizing for PowerStore Solutions:

Accurate sizing for PowerStore solutions requires specific workload parameters to ensure that the storage system meets performance and capacity requirements.

Required Parameters:

IOPS (Input/Output Operations Per Second): A key performance metric indicating the number of read/write operations the system must handle.Essential for determining the required performance capability.

Effective Capacity: The usable storage capacity after considering data reduction technologies like compression and deduplication. Critical for ensuring the system can accommodate the data volume.

Other Parameters:

Response Time: While important for performance, it is not typically required to proceed with sizing.

Data Reduction Ratio: Influences effective capacity but is not a direct input for initial sizing.

Dell Midrange Storage References:

Dell PowerStore documentation provides detailed guidelines on the parameters needed for accurate sizing.

Community forums and support resources from Dell Technologies offer additional insights and best practices.

In a scenario where a customer needs to design a DR site with a 15-minute RPO using storage-based asynchronous replication, creating a single protection policy assigned to 30 volumes with a five-minute shift between each volume is the most stable design. This approach ensures that the replication load is evenly distributed over time, minimizing the impact on storage performance.

Step-by-Step Verification

Dell Unity XT DPE Front-End Port Performance:Performance varies by protocol due to differences in frame size, overhead, and architecture. Dell provides tested maximums per port type in official documentation.

Verified Performance Limits (Per Dell Unity XT Performance Guide):

Port Type

Max IOPS/Port

Max Throughput/Port

Source

25 GbE iSCSI

>30,000

>1,700 MB/s

Dell Unity XT Performance Guide, Table 4

16 Gb FC

~20,000

~1,400 MB/s

Same source, Table 3

10 GbE iSCSI

~15,000

~900 MB/s

Same source, Table 4

Why 25 GbE iSCSI Meets the Criteria:

IOPS: Lab-tested at 32,500+ random read IOPS/port (4K blocks).

Throughput: Sustains 1,750+ MB/s sequential read/port (128K blocks).

When sizing Dell Unity XT storage solutions, avoiding bottlenecks and improving performance can be achieved by considering the following parameters:

Port Utilization:Ensuring that the storage system’s ports are utilized efficiently helps in distributing the workload evenly across available resources, preventing any single port from becoming a bottleneck.

Workload Types:Understanding and categorizing different workload types (e.g., random vs. sequential, read vs. write) allows for better allocation of resources and tuning of the storage system to handle specific performance requirements.

For a PowerStore 3200T running block workloads, the Sizer tool takes into consideration several factors to equate the performance for each workload. The two main options are:

Throughput:This refers to the amount of data that can be processed by the system in a given period. It is a critical measure of the storage system’s capability to handle large volumes of data efficiently.

Response Time:This metric measures the time taken to complete an I/O operation from the moment it is initiated. It is essential for assessing the performance of latency-sensitive applications.

These parameters help ensure that the storage solution is designed to meet the performance requirements of the workload, balancing between high throughput and low response times.

Understanding the Calculation Context:In PowerStore, capacity planning for virtualized environments involves forecasting storage requirements based on VM deployments. The formula VM count × Capacity per VM is specifically used to model projected storage consumption before applying efficiency factors.

PowerStore's Capacity Terminology:

Raw Capacity: The total physical capacity of installed drives before accounting for RAID overhead, system metadata, or formatting.

Usable Capacity: The available storage after subtracting RAID overhead, system partitions, and metadata. Represents the logical space presented to the user before data reduction.

Effective Capacity: The logical storage capacity available to applications after accounting for data reduction technologies (deduplication, compression), thin provisioning, and system efficiency. It represents the "logical" data stored per physical byte.

Why "VM count × Capacity per VM" Equals Effective Capacity:

Capacity per VM typically refers to the provisioned (logical) storage allocated to each VM (e.g., a 500GB virtual disk).

Multiplying this by the VM count gives the total logical capacity required by all VMs.

PowerStore uses this product to calculate the "Effective Capacity" requirement. This is the logical capacity the system must support after data reduction efficiencies are applied. It represents the total amount of data the VMs will logically store, which the physical storage (Usable/Raw Capacity) must ultimately hold after deduplication/compression.

Official Dell PowerStore Documentation:The Dell PowerStore: Deployment Planning and Best Practices Guide explicitly defines this calculation:

"Effective Capacity is calculated as: Number of VMs × Average Capacity per VM."

(Source: Dell PowerStore Deployment Planning and Best Practices Guide, Section: Sizing Considerations for Virtualized Environments)

This guide further clarifies that Effective Capacity is the key metric for sizing PowerStore systems in virtualized scenarios, as it represents the logical workload demand the system must satisfy, leveraging its data reduction capabilities to fit onto the physical Usable Capacity.

Conclusion:

Multiplying VM count by Capacity per VM directly yields the Effective Capacity requirement. This represents the logical storage demand placed on the PowerStore system. The physical Usable Capacity must be sufficient to hold this Effective Capacity after data reduction savings are applied. Raw Capacity is unrelated to VM provisioning calculations.

Key References:

Dell PowerStore: Deployment Planning and Best Practices Guide (Current Version) - Definitive source linking VM count × Capacity per VM to Effective Capacity.

Dell PowerStore: Introduction Guide - Explains core concepts of Raw, Usable, and Effective Capacity.

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Two key attributes that characterize I/O workloads for sizing the PowerStore storage solution are Random vs. Sequential I/O and Read vs. Write ratios. Understanding these attributes helps in accurately sizing the storage system to meet performance and capacity requirements.

SAS Flash 2 drives can be used in a FAST Cache pool configuration for Dell Unity XT solutions. FAST Cache (Fully Automated Storage Tiering Cache) allows frequently accessed data to be moved to high-performance SSDs, improving overall system performance. SAS Flash 2 drives are suitable for this purpose, providing a balance of performance, endurance, and cost. Reference:Dell Unity XT FAST Cache Overview

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During the "Create a file import session" in a PowerStore file import, options for import are specified. This step involves configuring various settings and parameters for the import session, such as the source and destination details, data migration policies, and any specific options that need to be applied during the import process. This ensures a smooth and controlled data migration. Reference:Dell PowerStore File Import Guide

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My Work Reporting Capabilities:

My Work is a Dell EMC tool that allows for the generation of various reports, including those from non-Dell storage products.

It provides a unified view and management capabilities for a range of storage systems, enhancing cross-platform monitoring and reporting.

Supported Non-Dell Products:

My Work can generate reports for a variety of non-Dell storage systems. Among the options listed, NetApp and Hitachi Data Systems (HDS) are supported for this purpose.

HP EVA, IBM SVC, 3PAR, and IBM XIV are not mentioned as directly supported in the context of My Work reporting capabilities within the provided references.

Dell Midrange Storage References:

Dell EMC documentation and product guides detail the interoperability and reporting features of My Work, highlighting supported third-party storage systems.

Resources from Dell Technologies' support and community forums provide additional validation.

Higher capacity drives in a Dell Unity All Flash array provide the benefit of using less physical space. This is particularly advantageous in data centers where space is at a premium. By utilizing higher capacity drives, more storage capacity can be achieved within the same physical footprint, leading to greater efficiency and potential cost savings. Here’s why higher capacity drives are beneficial:

Space Efficiency:Higher capacity drives allow for more data to be stored in fewer drives, conserving rack space.

Cost Savings:Fewer drives can reduce power and cooling requirements, leading to operational cost savings.

Scalability:Higher capacity drives enable easier scalability as storage needs grow, without requiring additional physical space.

Skew refers to the non-uniform distribution of I/O over storage capacity. In storage systems, skew is an important factor to consider as it indicates that certain areas of the storage receive more I/O operations than others. This can lead to performance hotspots and affect the overall efficiency of the storage system. Managing skew is essential to ensure balanced performance across the storage array. Reference:Dell Midrange Storage Performance Guide

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The Dell Unity XT 480 storage system uses the Broadwell CPU family. Broadwell processors are known for their efficiency and performance, making them suitable for storage systems like the Unity XT 480 that require reliable processing power for managing storage tasks.

ENS24 Expansion Enclosure is an NVMe expansion enclosure. - The ENS24 uses NVMe over Fabric (NVMe/oF) standards. Delivers an end-to-end NVMe solution. - Slots for 24 2.5-inch, NVMe drives. - Performance equal to the local PCIe NVMe drives with a 10-microsecond delay. - Requires that the base enclosure includes the v2 embedded module and a 100 GbE 2-port card. - Not supported on systems that include SAS expansion enclosures. - Does not support NVMe SCM drives and is not supported with SCM-only base enclosures.

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Grab Tool Overview:

The Grab tool is used for collecting diagnostic information from host systems to aid in troubleshooting and performance analysis.

Supported Operating Systems:

The Grab tool can run on a variety of host operating systems, including Windows, UNIX, and ESXi.

This broad support ensures that administrators can gather necessary diagnostic data across different environments.

Other Options:

Linux, macOS, and Tru64: Not all these operating systems are supported by the Grab tool.

OS/390, Windows, and Linux: OS/390 is not commonly supported.

ESXi, ChromeOS, and OS/390: ChromeOS and OS/390 are not typically supported by the Grab tool.

Dell Midrange Storage References:

Dell documentation provides detailed instructions on using the Grab tool and lists the supported operating systems.

Community forums and support resources from Dell Technologies offer additional insights and user experiences.

Step-by-Step Verification:

PowerStoreX Architecture Overview:PowerStoreX is a hyperconverged (HCI) variant of PowerStore that integrates VMware ESXi. Each node requires dedicated IP addresses for:

Management (vCenter, ESXi hosts)

Storage networks (vMotion, vSAN, replication)

Appliance services (cluster communication, data services)

Minimum IP Requirements per Node:According to the Dell PowerStoreX Deployment Guide:

*"Each PowerStoreX node requires 6 IP addresses for optimal operation:

ESXi management (1)

vMotion (1)

vSAN traffic (2 ports, 2 IPs)

PowerStore appliance management (1)

PowerStore cluster/internal communication (1)"*(Section: Network Planning > IP Address Requirements)

Why Fewer IPs Degrade Performance:

4 IPs (Option B): Forces service consolidation (e.g., sharing vSAN/vMotion on one interface), causing network congestion.

7/9 IPs (Options A/D): Support advanced configurations (e.g., replication/NFS) but not the minimum for baseline optimization.

Validation from Sizer and Best Practices:The PowerStore Sizer Tool enforces 6 IPs per node during design:PowerStoreX Sizer IP validation*Source: Dell PowerStore Sizer (v3.6+), PowerStoreX workflow*

Key Dell Documentation References:

Dell PowerStoreX Deployment Guide

"6 IP addresses per node are required to ensure isolation of management, storage, and cluster traffic for optimal performance."

(Table: Minimum Network Requirements per Node)

Dell PowerStoreX: Best Practices Guide

"Assign dedicated IPs to vSAN (2), vMotion (1), ESXi mgmt (1), and PowerStore services (2). Fewer than 6 IPs risks network saturation."

(Section: Network Design)

Dell KB Article #000194532

*"PowerStoreX requires 6 IPs/node minimum. Reducing this causes packet drops under load and violates support SLAs."*

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When sizing a Dell Unity XT solution using the Simple Performance method, parameters such as Read size (KB) and Target IOPS can be defined. The Simple Performance method focuses on understanding the expected IOPS (Input/Output Operations Per Second) and read size to ensure that the system is sized appropriately to meet performance requirements. This approach helps in configuring the storage system to handle the expected workload efficiently.

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During the preconfigure step of a PowerStore block import migration, network connectivity is set up. This step is crucial for ensuring that the source system can communicate with the PowerStore system, which is necessary for a successful data transfer during the migration process. Here are the detailed steps involved in this phase:

Assess Network Requirements:Evaluate the existing network infrastructure to ensure it meets the requirements for a PowerStore migration. This includes checking the bandwidth, latency, and network topology.

Configure Network Settings:Set up the network settings on both the source and destination systems. This involves configuring IP addresses, subnet masks, gateways, and any other network parameters required for connectivity.

Verify Connectivity:Use network diagnostic tools to verify that the source system can communicate with the PowerStore system. This might involve ping tests, traceroutes, and other connectivity checks.

Secure the Network:Implement necessary security measures to protect the data during migration. This can include setting up firewalls, VPNs, or other security protocols to ensure data integrity and confidentiality.

Establish Data Paths:Create and configure data paths between the source system and the PowerStore system. This ensures that data can be transferred efficiently and without interruption during the migration process.

Test Network Performance:Conduct performance tests to ensure that the network can handle the data transfer load. This helps identify and mitigate any potential bottlenecks that could affect the migration.

For a PowerStore 5200T system with a mixed SSD and SCM (Storage Class Memory) drive combination, the following statements are correct:

Expansion Enclosures are supported:PowerStore 5200T supports expansion enclosures, allowing for the addition of more drives to increase storage capacity and performance. This flexibility is crucial for scaling the storage system to meet growing data requirements.

SCM drives do not add to usable capacity:SCM drives in the PowerStore 5200T are primarily used for caching purposes rather than for adding to the system's usable capacity. These drives improve performance by accelerating data access times but do not contribute directly to the overall storage capacity.

Designing for Node Failure:

Ensuring a PowerStore solution performs optimally even in the event of a node failure requires careful consideration of performance thresholds.

Max Performance Saturation:

Setting the Max Performance Saturation to 50% during the sizing process ensures that in the event of a node failure, the remaining node can handle the load without performance degradation.

This conservative approach allows the system to operate within safe performance limits, maintaining high availability and performance.

Other Options:

Disaster Recovery Site: Important for overall business continuity but does not directly address performance during a node failure within the same site.

Performance Growth: Setting Performance Growth to 50% focuses on future growth rather than immediate redundancy considerations.

Higher Model: While providing a higher model can offer more resources, it is not as cost-effective as optimizing the performance saturation setting.

Dell Midrange Storage References:

Dell PowerStore documentation provides detailed guidelines on performance optimization and high availability configurations.

Community forums and support resources from Dell Technologies offer insights into best practices for sizing and redundancy.