DEE-1111 Sample Questions Answers

The -precopy option in the relink command can be used when you want to start copying data to the target devices immediately after the link operation. This can be useful in situations where additional volumes have been added, increasing the link to full copy time. By using -precopy, you ensure that the data starts copying immediately, preventing potential issues.

When vWitness and Array Witness options are deployed in the same operating environment simultaneously, SRDF/Metro favors the Witness option over the Array Witness option. This is because the Witness option provides a higher level of protection against split-brain scenarios and data loss than the Array Witness option. The Witness option uses a third-party server to monitor the health and connectivity of both SRDF/Metro arrays and to arbitrate in case of a failure. The Array Witness option uses a third array to store configuration information and to arbitrate in case of a failure. However, the Array Witness option does not monitor the health and connectivity of both SRDF/Metro arrays, and it requires manual intervention to resume SRDF/Metro replication after a failure.

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

If an administrator implemented SYMACLs on a PowerMax using host-based Access IDs and is no longer able to run SYMCLI commands against the volumes belonging to a host, one possible reason could be that the SYMAPI options file was manually modified with the wrong host ID. The SYMAPI options file contains configuration settings for Solutions Enabler, including host IDs for access control. If this file is incorrectly modified, it could prevent the administrator from running SYMCLI commands against certain volumes34. References: Dell EMC PowerMax and VMAX All Flash: Embedded Management, Role Based Access Control on PowerMax – Storage Intelligence

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

SRDF device used for Concurrent SRDF environments =R21

SRDF device used for SRDF/Star environments =R11

SRDF device used for Cascaded SRDF environments =R22

A dual personality SRDF device is a device that can act as both an R1 and an R2 device in different SRDF configurations. There are three types of dual personality SRDF devices: R21, R11, and R22.

• An R21 device is an R2 device that is paired with another R1 device in a different SRDF group. This allows the R21 device to receive updates from the primary site and send updates to the secondary site. An R21 device is used for Concurrent SRDF environments, which provide simultaneous disaster recovery and data migration capabilities.For example, an R21 device can be used to migrate data from one array to another while maintaining a synchronous copy of the data on a third array.1
• An R11 device is an R1 device that is paired with another R1 device in a different SRDF group. This allows the R11 device to receive updates from the primary site and send updates to the tertiary site. An R11 device is used for SRDF/Star environments, which provide three-site disaster recovery capabilities with a single hop between any two sites.For example, an R11 device can be used to create a synchronous copy of the data on a secondary site and an asynchronous copy of the data on a tertiary site.2
• An R22 device is an R2 device that is paired with another R2 device in a different SRDF group. This allows the R22 device to receive updates from the secondary site and send updates to the tertiary site. An R22 device is used for Cascaded SRDF environments, which provide three-site disaster recovery capabilities with two hops between the primary and tertiary sites.For example, an R22 device can be used to create an asynchronous copy of the data on a secondary site and another asynchronous copy of the data on a tertiary site.3

References:

• Dell EMC SRDF Introduction - Dell Technologies Partner Portal
• Dell EMC PowerMax and VMAX All Flash: SRDF Product Guide
• Dell EMC PowerMaxOS Performance Guide

The steps in sequence as part of key management for a drive failure on a PowerMax array are as follows:

• Spare drive invoked against failed drive. This step involves the system automatically selecting a spare drive and starting the sparing operation to rebuild the data from the failed drive.The spare drive is encrypted with a temporary key that is stored in the embedded key manager.1
• 1st entry in audit log.This step involves the system logging the sparing operation and the temporary key generation in the audit log, which records all key management activities and events.1
• Sparing operation is completed. This step involves the system completing the data rebuild and marking the spare drive as a permanent replacement for the failed drive.The spare drive becomes part of the RAID group and inherits the same properties as the failed drive.1
• Key is deleted from the repository when failed drive is removed. This step involves the system deleting the Data Encryption Key (DEK) of the failed drive from the embedded key manager when the failed drive is physically removed from the array.The DEK is a unique 256-bit AES-XTS key that is used to encrypt and decrypt data on each drive.1
• 2nd entry in audit log.This step involves the system logging the DEK deletion and the failed drive removal in the audit log.1
• Key is generated for the replacement drive when installed. This step involves the system generating a new DEK for the replacement drive when it is installed in the array.The new DEK is stored in the embedded key manager and used to encrypt and decrypt data on the replacement drive.1

References:

• Dell EMC PowerMax and VMAX All Flash: Data at Rest Encryption

 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

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

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.

The metrics that are recommended to start analyzing the overall efficiency of the array due to cache are array-level % Hit and % Cache WP. The array-level % Hit metric shows the percentage of read requests that are satisfied from the cache memory, without accessing the physical disks. A high % Hit value indicates that the cache is effective in reducing the read latency and improving the performance. The % Cache WP metric shows the percentage of cache memory that is occupied by write pending data, which is data that has been written to the cache but not yet destaged to the physical disks. A high % Cache WP value indicates that the cache is under pressure and may not have enough space to accommodate new write requests, which can lead to performance degradation. By monitoring these two metrics, a storage administrator can evaluate the overall efficiency of the array due to cache and identify any potential issues or bottlenecks.

References:

• System efficiency overview | Dell PowerMax: Data Reduction | Dell Technologies Info Hub
• Metrics (PowerMax & VMAX) - VMware Docs
• Dell EMC PowerMax storage
• Replication cache | Dell EMC PowerMax and VMAX All Flash: TimeFinder SnapVX Local Replication

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