DEE-1111 Expert - PowerMax and VMAX All Flash Solutions Questions and Answers

A company plans to implement SRDF/Star, which is a three-site replication solution that provides continuous data protection and disaster recovery capabilities. It is currently using SRDF/S between their two data centers, which are located within 200 kilometersand use synchronous replication. It is setting up a third data center and wants to have at least two identical copies of its data in case of a primary site failure. The third site can be located anywhere in the world and use asynchronous replication. The condition that is needed for the connection between the first two sites and the third site is that the link must be able to transport the delta set of the Recovery Point Objective (RPO) within the company’s Recovery Time Objective (RTO). The delta set is the amount of data that has changed since the last successful replication cycle. The RPO is the maximum acceptable amount of data loss measured in time. The RTO is the maximum acceptable amount of time to restore normal operations after a disaster. The link must have enough bandwidth and latency to ensure that the delta set can be transferred within the RTO without exceeding the RPO.

References:

• SRDF Star software uses and best practices
• SRDF/STAR
• Remote replication using SRDF

 If utilization increases by 10% for both systems A and B, where system A has a current utilization of 10% and system B has a current utilization of 70%, the response times for systems A and B would not necessarily increase linearly with utilization. The exact impact on response times would depend on various factors including workload characteristics, system configuration, and resource contention among others34. However, without specific details on these factors, it’s not possible to provide an accurate prediction for the new response times. References: PowerMax and VMAX All Flash: Storage Resource Pool (SRP) Effective Used Capacity threshold alert, Service levels and eNAS | Dell EMC PowerMax and VMAX All Flash: eNAS Best Practices

In an SRDF/Metro Smart DR configuration, the Fault-Aware Witness gives a higher priority to Bias when selecting the winning array. The bias settings for the devices are used to determine the preferred winner in the event of a failure2. The preferred winner is the side that has priority when requesting the lock from the witness instance2. References: Dell EMC PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices

https://infohub.delltechnologies.com/l/dell-emc-powermax-and-vmax-non-disruptive-migration-best-practices-and-operational-guide-1/ndm-overview

 When maintenance tasks at the R1 data center require the array to be offline, a Swap operation should be executed on the Metro RDF pairs. This operation allows for a planned outage without affecting application I/O by swapping the roles of R1 and R2 devices. 

In an SRDF/Metro configuration, if the host is cross-connected and the R2 device becomes Not Ready, the host continues to have read/write access to the R1 device12. This is because SRDF/Metro is designed to provide high availability and continuous data access. If one device becomes inaccessible, the host can still access the other device12. References: SRDF/Metro | SAP Landscape Consolidation with Dell Components, Understanding bias | Dell EMC PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices

 The most likely cause of this behavior is QFULL responses of the FA ports. When additional hosts are zoned to certain front-end adapters, the FA ports may not be able to handle the increased I/O requests, resulting in QFULL responses. This can cause non-linear variations in throughput and sometimes a drop in throughput of more than 20%. References: Dell EMC PowerMax: Service Levels for PowerMaxOS

While using DELL EMC Data Erasure on a PowerMax, the minimum number of overwrites needed to support compliance with internal policies and regulatory requirements is 3. The application has prompts and notifications. Such as the option to choose the number of Media Eraser ‘wipes’ (3x times, 5x times or 7x times)1. References: Dell EMC Community Network

Before configuring Access Control, the security administrator must define the User Access ID for the Admin User. This is a necessary step to ensure that the administrator has the necessary permissions to perform this operation.

PowerMax & VMAX All-Flash Storage Technical Documentation, Dell EMC PowerMax and VMAX All Flash: Embedded Management

 In an SRDF/Metro configuration with bias setting, if there is a failure at the R1 array (which is configured as the bias side), the R2 device automatically becomes the active device. This means that even if there’s a failure on the R1 side, operations can continue on the R2 side without interruption, ensuring high availability.

https://infohub.delltechnologies.com/l/dell-emc-powermax-and-vmax-all-flash-srdf-metro-overview-and-best-practices-1/understanding-bias

The alert settings required are a first level warning at 10 ms and a second level critical alert at 15 ms. These settings will ensure that high I/O response times for a specific storage group are tracked and appropriate actions are taken when the response times exceed the specified thresholds. References: Dell EMC PowerMax: Service Levels for PowerMaxOS

 In a SRDF/Metro deployment in a clustered host configuration, when the RDF link state is partitioned and the R1 side has full read/write capability to the application, the R2 device also has full read/write capability to the application. With SRDF/Metro, both R1 and R2 devices may then appear as a single virtual device across the two SRDF paired arrays for host presentation. With both the R1 and R2 devices being accessible, the host or hosts (in the case of a cluster) can read and write to both R1 and R2 devices with SRDF/Metro ensuring that each copy remains current, consistent, and addressing any write conflicts which may occur between the paired SRDF devices23. References: Dell EMC PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices, Deploying Dell EMC SRDF/Metro Smart DR with Microsoft SQL Server for Physical and Virtual Environments

For an SRDF/Metro personality swap, the SRDF/Metro devices must be Read/Write (RW) on the link. This ensures that data can be read from and written to the devices during the swap operation.

References: SRDF/Metro overview | Dell EMC PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices, Understanding bias | Dell EMC PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices