EMC D-MSS-DS-23 Dell Midrange Storage Solutions Design 2023 Exam Practice Test

The maximum supported drive configuration in the base enclosure of the PowerStore 3200T includes 23 NVMe SSDs and 2 NVMe NVRAM. This configuration provides high performance and low latency, suitable for demanding workloads.

When planning and sizing a Midrange storage solution, two key guidelines for optimal performance are to consolidate workloads and design for resilience. Consolidating workloads helps in maximizing the utilization of storage resources, reducing overhead, and improving performance. Designing for resilience ensures that the storage solution can handle failures and continue to operate effectively, maintaining data availability and performance. These practices are critical for achieving reliable and efficient storage solutions. Reference:Dell Midrange Storage Planning Guide

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The simple performance path in the Dell Unity XT sizer tool uses predefined configurations to streamline the sizing process.

This path considers various parameters to estimate the achievable IOPS rate and overall system performance.

Drive Busy Percentage:

The simple performance path assumes a maximum of 80% drive busy percentage to determine the achievable IOPS rate.

This threshold ensures that the drives are utilized efficiently without overloading, balancing performance and longevity.

Other Percentages:

Lower percentages (50%, 60%, 70%) would be too conservative and might result in under-utilization of the system’s capabilities.

Dell Midrange Storage References:

Dell Unity XT documentation and sizer tool guides provide detailed information on performance metrics and assumptions used for sizing.

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

RAID 6 Dynamic Pool Configuration:

RAID 6 provides high data protection by using double parity, allowing for two drive failures without data loss.

Minimum Number of Drives:

A RAID 6 dynamic pool in Dell Unity XT systems requires a minimum of 8 drives to configure. This includes 2 drives for parity and 6 drives for data storage.

Drive Configuration:

The minimum configuration ensures that the system can provide the necessary data protection and redundancy while maintaining performance.

Dell Midrange Storage References:

Dell Unity XT documentation provides detailed guidelines on RAID configurations and the minimum requirements for various RAID levels.

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

Recovery Point ObjectiveWhen you set up an asynchronous replication session, you can configure automatic synchronization based on the RPO. You can specify an RPO from a minimum of 5 minutes up to a maximum of 1440 minutes (24 htours).

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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.

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).

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.

According to Dell PowerStore documentation (PowerStore OS 2.0+):

A Base Volume Family logically groups:

Original volume (source)

Snapshots (point-in-time copies)

Thin clones (writable snapshots)

Replication targets (synchronized copies for disaster recovery)

This unified structure simplifies management and ensures data consistency across all derived volumes.

 Source: Dell PowerStore Administration Guide (Section: Volume Families, Page 97).

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.

The tool that a Solution Architect must use to check the compatibility of a new storage solution with an existing infrastructure is E-Lab Navigator. E-Lab Navigator is a comprehensive online database provided by Dell that includes compatibility information for various hardware and software configurations. It helps ensure that new storage solutions are compatible with existing infrastructure, reducing the risk of integration issues. Reference:Dell E-Lab Navigator Overview

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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.

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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The Unity Designer tool helps in designing storage solutions by taking specific inputs and generating detailed outputs. Here are the inputs and outputs of the Unity Designer tool:

Inputs:

Sales Order:Details about the customer’s purchase order.

Sizing XML File:An XML file that contains sizing information and requirements for the storage solution.

System Configuration PDF File:A PDF file that outlines the system configuration and specifications.

Outputs:

Detailed Design:A comprehensive design document that outlines the storage solution, including configuration details and recommended setups.

Excel Configuration Guide Report:An Excel report that provides a step-by-step guide for configuring the system based on the inputs provided.

The maximum throughput per port in backend 12 Gb SAS (Serial Attached SCSI) ports in Dell Unity XT arrays is 2500 Mbps. SAS ports are used to connect storage devices and provide high-speed data transfer capabilities:

12 Gb SAS Standard:The 12 Gb SAS standard supports high data transfer rates, making it suitable for enterprise storage systems that require robust performance and reliability.

Performance Metrics:Each 12 Gb SAS port can achieve up to 2500 Mbps, which translates to approximately 2.5 Gbps of throughput, supporting high-performance storage operations.

In the PowerStore sizing tool, the default Data Reduction Ratio (DRR) values for block and file workloads are Block = 4:1 and File = 2:1. These values represent the expected reduction in data size due to compression and deduplication, which helps in planning the storage capacity and performance requirements effectively. Reference:Dell PowerStore Sizing Tool Documentation

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Sizer Tool Paths:

The Dell Unity XT sizer tool offers multiple paths for configuring storage solutions, each tailored to different user needs and expertise levels.

Quick Configuration:

The Quick Configuration path uses predefined configurations based on array model, capacity points, random workloads, RAID type, and drive type.

This path simplifies the sizing process by providing users with recommended configurations that align with common use cases and performance requirements.

Other Paths:

Advanced Performance: Allows for detailed customization of performance parameters.

Simple Performance: Focuses on basic performance metrics without predefined configurations.

System Designer: Provides comprehensive design options for complex scenarios.

Dell Midrange Storage References:

Dell Unity XT documentation provides detailed guidelines on using the sizer tool and the different configuration paths available.

Additional resources from Dell Technologies' support and community forums offer insights into best practices for using the sizer tool.

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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Cascade replication on the Dell Unity XT platform describes the process where a block resource is replicated asynchronously from one site to another in a sequential manner. Here’s how it works:

Site A to Site B:The block resource is first replicated asynchronously from Site A to Site B.

Site B to Site C:After the replication from A to B is complete, the resource is then replicated from Site B to Site C.

Site C to Site D:Finally, the resource is replicated from Site C to Site D.

This cascade replication method allows for efficient data protection and disaster recovery across multiple sites.

In Dell Unity XT storage processors, SAS (Serial Attached SCSI) ports are used to move data to and from the backend drives. SAS ports provide a high-speed and reliable connection between the storage processors and the physical drives, ensuring efficient data transfer and access. This connectivity is crucial for maintaining the performance and scalability of the storage system. Reference:Dell Unity XT Architecture

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CloudIQ is a cloud-based application that provides frequent, dynamic, and nondisruptive content updates to users. It offers proactive monitoring, predictive analytics, and detailed health scores for Dell storage environments, including PowerStore and Unity systems. CloudIQ helps users maintain optimal system performance by delivering real-time insights and alerts about potential issues before they impact operations. Here’s how CloudIQ benefits users:

Frequent Updates:CloudIQ continuously gathers and analyzes data from connected systems, providing up-to-date information and insights.

Dynamic Content:The tool dynamically adapts to changing conditions in the storage environment, offering relevant recommendations and updates.

Nondisruptive:All updates and insights provided by CloudIQ are nondisruptive, ensuring that there is no interruption to the system’s operations.

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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File Data Migration Tools:

Migrating file data from legacy systems to new arrays requires reliable tools that can handle large volumes of data efficiently.

Robocopy for Windows Hosts:

Robocopy (Robust File Copy) is a powerful command-line tool in Windows that supports extensive options for copying and synchronizing files and directories.

It is well-suited for migrating file data from a legacy VNX array to a new Dell Unity XT array, ensuring data integrity and consistency.

Other Tools:

SANCopy: Used for SAN data migration and not specific to file data.

Rsync: Commonly used for Linux/Unix systems rather than Windows hosts.

Dell Midrange Storage References:

Dell Unity XT documentation and migration guides provide detailed instructions on using Robocopy for file data migration.

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

Dell Unity XT offers both synchronous and asynchronous replication to protect data and ensure business continuity.

Synchronous replication is used for zero RPO, ensuring no data loss, but it is typically limited to shorter distances due to latency concerns.

Asynchronous replication is suitable for longer distances and provides near real-time data protection with a minimal RPO.

Distance Considerations:

The distance between Boston and Cambridge (8 km) is suitable for synchronous replication, providing zero RPO.

The distance between Boston and New York (342 km) is better suited for asynchronous replication due to latency, ensuring data recovery with a minimal RPO, such as 15 minutes.

Optimal Replication Strategy:

Synchronous replication from Boston to Cambridge ensures zero RPO for critical data protection.

Asynchronous replication from Boston to New York provides additional data protection with a 15-minute RPO, suitable for longer-distance disaster recovery.

Dell Midrange Storage References:

Dell Unity XT documentation and best practices provide detailed guidelines on configuring synchronous and asynchronous replication.

Community forums and support resources from Dell Technologies offer insights into real-world implementation strategies.

Whenonly two SAS ports are available on each Storage Processor (SP) in a Dell Unity XT Disk Processor Enclosure (DPE), therecommended order for connecting DAEsis toalternate DAEs between buses (SAS Bus 0 and SAS Bus 1)to achieve balanced performance and availability.

✅Recommended Order (per Dell EMC Best Practices Guide):

DAE 1→ Connect toSAS Bus 1

DAE 2→ Connect toSAS Bus 0

DAE 3→ Connect toSAS Bus 1

✅Why this order?

Alternating DAEs between buses ensures even distribution of I/O load across the two buses.

It enhances fault tolerance and reduces the risk of performance bottlenecks or single points of failure.

This arrangement follows Dell’s best practice to alwaysbalance the number of DAEs across SAS buseswhenever possible.

❌Why not the other options?

A and D– These do not alternate buses, leading to unbalanced bus usage and potential bottlenecks.

B– Does not balance DAEs evenly across the two buses.

C– Alternates the buses for each DAE, following the recommended best practice for2-port DPE configurations.

✅Documentation Reference:

Dell EMC Unity XT Best Practices Guide– Highlights bus load balancing for optimal performance.

Dell EMC Unity XT Hardware Installation Guide– Provides diagrams and connection orders for DAE cabling.

Dell EMC Unity XT Hardware Overview– Confirms the 2-port DPE recommended configurations.

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Dell Unity XT DPE (Disk Processor Enclosure) front-end port connectivity options that can support up to 45000 IOPS per port and up to 1500 MB/s include both 16 Gb Fibre Channel (FC) and 25 GbE iSCSI. These connectivity options provide the necessary performance and bandwidth to handle high IOPS and throughput demands:

16 Gb Fibre Channel (FC):Known for high performance and low latency, 16 Gb FC ports are widely used in enterprise storage environments to support high IOPS and bandwidth.

25 GbE iSCSI:25 Gigabit Ethernet iSCSI ports offer high-speed connectivity for IP-based storage networks, capable of supporting high throughput and IOPS requirements.