DEE-1111 Expert - PowerMax and VMAX Family Solutions Exam Questions and Answers

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

 The symrdf split command is used to suspend SRDF/A replication and make both R1 and R2 devices read/write enabled. This is useful for testing purposes or for creating point-in-time copies of data on both sides. The symrdf establish command can be used to resume SRDF/A replication after a split operation. The exhibit shows that both R1 and R2 devices are read/write enabled and have a Split status, which indicates that a symrdf split command was issued next2

In a Concurrent SRDF/Star environment where the production data on R11 devices are replicated to two R2 devices in two remote arrays, SRDF/S links must be configured between Site 3 and Site 2. This is because in a Concurrent SRDF/Star configuration, there are two target sites and one source site. If there’s a failure, the source site can switch to either of the target sites based on the business continuity plan1. References: Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide, SRDF Star software uses and best practices - Dell

 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.

In an SRDF/Star configuration, all SRDF/Star device pairs must be of the same geometry and size. This is because SRDF/Star uses concurrent SRDF to maintain synchronous and asynchronous SRDF sessions between three arrays. The devices in these sessions must have identical geometry to ensure data consistency56. References: Dell EMC Solutions Enabler 9.2 SRDF Family CLI User Guide, SRDF/Metro overview | Dell EMC PowerMax and VMAX All Flash: SRDF/Metro Overview and Best Practices

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

Fast Write is a Dell EMC technology that improves Fibre Channel (FC) replication between sites in a SRDF/S configuration. When a write I/O is issued by the host to the R1 device, SRDF with Fast Write acknowledges the write to the host as soon as the data is stored in the R1’s cache and transmitted to the R2’s cache. This results in reduced latency and improved performance for FC replication between sites.

https://www.delltechnologies.com/asset/en-us/products/storage/industry-market/h17118_dell_emc_powermax_family_overview.pdf

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

R11 devices are included in a Cascaded SRDF environment. In a cascaded SRDF configuration, the R1 device at the primary site is paired with an R11 device at the secondary site, which is then paired with an R2 device at the tertiary site2. References: NDM overview | Dell EMC PowerMax and VMAX: Non-Disruptive Migration Best Practices and Operational Guide | Dell Technologies Info Hub

 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

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

The symauth command is used to manage user authorization for SYMCLI commands. The exhibit shows the output of the symauth -list command, which displays the user groups and access types defined for SYMCLI commands. The output shows that there are two user groups: AdminGrp and EmcMgmtGrp. The AdminGrp group has ADMINRD access type, which means that users in this group can run any SYMCLI command with read-only access. The EmcMgmtGrp group has BASECONTROL access type, which means that users in this group can run only a subset of SYMCLI commands with read/write access. Therefore, the correct description of a possible configuration created by SYMACL is hosts that are part of AdminGrp group2

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.