If an administrator has added custom SSL certificates and each time a client connection is made, default certificates are used, then ‘restart storsrvd’ must be completed. This is because changes to SSL certificates often require a restart of the service that uses them in order for the new certificates to be correctly loaded and used for future client connections1.

 When the cache space fills up, I/O will be queued until an empty cache slot is available. This is because PowerMax operates as a cache-centric architecture, where all data is passed through cache before being stored on disk. Cache is used to buffer incoming and outgoing data, as well as to support various functions such as replication and data reduction. When cache is full, the array cannot accept any more data until some cache slots are freed up by flushing data to disk or invalidating stale data. Therefore, answer B is correct.

A, C, and D are incorrect because they do not describe what happens when cache space fills up. I/O will not be serviced at the speed of the destination device (A), as this would bypass the cache and degrade performance. Cache is not permanently flushed © or temporarily disabled (D), as this would result in data loss or corruption.

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

During a Non-Disruptive Migration (NDM), issuing the ReadyTgt SYMCLI command to the migrating Storage Group completes the migration by removing the migrated application resources from the source array2. This command is typically issued after all data has been synchronized from the source to the target array and application I/O has been switched to thetarget array2. References: NDM overview | Dell EMC PowerMax and VMAX: Non-Disruptive Migration Best Practices and Operational Guide | Dell Technologies Info Hub

An application owner is experiencing performance issues for their application. Unisphere for PowerMax is showing the storage group is compliant with the current Service Level. This means that the performance issue is not caused by the storage system, but by some other factor in the environment, such as network congestion, host configuration, or application workload. One possible way to address the performance issue is to redistribute the application to other front-end host ports on different directors. This can help balance the workload across multiple paths and avoid potential bottlenecks or contention on a single port or director. Unisphere for PowerMax provides a Performance Plan feature that can analyze the current configuration and suggest optimal port allocation for each storage group based on historical data and best practices.

References:

• Understanding Performance Management
• Dell EMC PowerMaxOS Performance Guide

The user has been assigned the RemoteRep role only. The RemoteRep role allows users to create, manage, and delete SRDF device pairs, as well as view array information, masking objects, device information, and RBAC rules2. However, it does not allow users to create and delete SRDF groups, which requires the StorageAdmin role. Therefore, answer C is correct.

A, B, and D are incorrect because they do not match the user’s profile. SecurityAdmin (A) role allows users to manage security settings such as authentication methods, certificates, RBAC rules, and audit logs2. Auditor (B) role allows users to view array information and audit logs only2. LocalRep (D) role allows users to create, manage, and delete TimeFinder SnapVX sessions from a source device2. None of these roles allow users to create and delete SRDF device pairs.

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

 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

Data Domain is the only external storage that can be connected to PowerMax using DX emulation. DX emulation is a specialized back-end DA emulation that handles SAN attached disks. DX directors are configured on existing PowerMax front-end Fibre Channel ports and are required to be implemented in pairs for high availability. DX emulation is used to support ProtectPoint technology, which integrates primary storage with Data Domain protection storage to accelerate backup and recovery. Therefore, answer A is correct1.

B, C, and D are incorrect because they are not external storage that can be connected to PowerMax using DX emulation. Unity (B), PowerStore ©, and Compellent (D) are primary storage arrays that do not support ProtectPoint technology or DX emulation.

An SRDF/Metro device pair was in an ActiveActive state, meaning that both the R1 and R2 devices were read/write accessible to the host or hosts. A link failure between arrays occurs, causing the device pair to become Not Ready (NR) on the SRDF link. SRDF/Metro responds by making the non-biased or R2 paired device inaccessible (not ready) to the host or host cluster, while keeping the biased or R1 paired device accessible (ready). This ensures that there is no data inconsistency or split-brain scenario between the two sites. The device pair enters an Active Bias state, which indicates that only one side of the pair is active and has a bias attribute set. The bias attribute determines which side of the pair remains accessible in case of a link failure. By default, the bias is set to the R1 side of the pair, but it can be changed using the symrdf set bias command. The application continues running on the R1 side, and the link failure is addressed. Once the link is restored, the device pair resumes the ActiveActive state and both devices become accessible again.

References:

• SRDF/Metro overview
• VMware vSphere Metro Storage Cluster (vMSC) with Dell PowerMax and Dell EMC VMAX SRDF/Metro
• Understanding bias

 In PowerMax, each RAID group is divided into 64 logical blocks known as TDATs (Thin Device Addressable Tracks). Each TDAT is configured to hold data at a given data reduction level, from 1:1 uncompressed data all the way to 16:11. References: Data Protection Schemes | Dell PowerMax: Reliability, Availability, and Serviceability | Dell Technologies Info Hub

he %Busy and Balance KPIs are the most important indicators of the BE performance on a PowerMax array. The %Busy metric shows the percentage of time that a BE director is busy processing I/O requests. A high %Busy value may indicate that the BE director is overloaded and cannot keep up with the demand. The Balance metric shows the difference in %Busy between the two BE directors in a pair. A high Balance value may indicate that the workload is not evenly distributed across the pair, which can lead to performance degradation. By monitoring these two KPIs, a storage administrator can identify and troubleshoot any potential issues with the BE performance.

References:

• PowerMax Performance Troubleshooting with Unisphere - Run a real time trace at the system level

During a Non-Disruptive Migration (NDM), when the migration is committed, the host access to the source array is removed by deleting the masking view. The masking view is a logical grouping of host initiators, storage ports, and a storage group (which contains volumes). Deleting the masking view removes the host’s access to the volumes on the source array12. References: Dell EMC PowerMax and VMAX: Non-Disruptive Migration Best Practices and Operational Guide, VMAX/PowerMax Non-Disruptive Migration (NDM) for the IBMi host platform | Dell US Support Knowledge Base Article