D-UN-DY-23 Dell Unity Deploy 2023 Exam Questions and Answers

The maximum number of replicated NAS servers supported for the Dell Unity XT 380 series in an asynchronous replication is 126. This is the same as the maximum number of NAS servers supported for the Dell Unity XT 380 series in general. Asynchronous replication is a method of replicating data between two Dell Unity systems with a configurable recovery point objective (RPO). It allows the source system to continue normal operations without waiting for the destination system to acknowledge the completion of the replication.

References: [Dell EMC Unity: Replication Technologies], [Dell EMC Unity: NAS Capabilities]

FAST VP (Fully Automated Storage Tiering for Virtual Pools) is a feature that automatically moves data within a storage pool based on the performance requirements and access patterns of the data. FAST VP data relocation runs in the background according to a user-defined schedule and rate. The schedule determines when the data relocation starts and ends, and the rate determines how much system resources are used for the data relocation. Users can set the Fast VP data relocation rate to High, Medium, Low, or None. High means that the data relocation has the highest priority and uses the most system resources, while None means that the data relocation is disabled. Fast VP data relocation does not run at all times, but only during the scheduled window. Fast VP optimizes data placement by moving 256 MB slices between disk tiers, not 1 GB slices. Users cannot enable or disable FAST VP at the LUN level, but only at the storage pool level.

References: [Dell EMC Unity: FAST Technology Overview], [Dell EMC Unity: Storage Pools and RAID Groups]

 Mixing FC and iSCSI protocols for the same host and array is not supported by Dell EMC Unity. This can cause issues with multipathing, failover, and performance. The best practice is to use one protocol per host and array pair. If the host needs to access both FC and iSCSI LUNs from different arrays, then separate vSwitches and port groups should be used for each protocol. References: Dell EMC Unity: Best Practices Guide1, page 19.

If the time difference between the current system (UTC) time and the NTP server time is too large (approximately 17 minutes), the user cannot configure an NTP server during initial configuration. The user will need to adjust the time while in “Set time manually” mode before changing to “Enable NTP synchronization”. This is to avoid potential issues with data replication, snapshots, and audit logs that rely on accurate time stamps. References: Dell EMC Unity: How to change System Time from ‘Set time manually’ option to NTP2, page 1.

The purpose of a Proxy NAS server is to access snapshot replicas on the destination side of a replicated file resource. A Proxy NAS server is a temporary NAS server that is created on the destination system to mount a snapshot replica of a replicated file system. This allows the user to access the data on the snapshot replica for testing, recovery, or other purposes. A Proxy NAS server does not increase performance or security of production NAS servers, nor does it access snapshots for testing production NAS servers.

References: [Dell EMC Unity: Replication Technologies], [Dell EMC Unity: File System Configuration]

VMware datastore is a logical container that holds virtual machine files and other data. There are three types of VMware datastore that can be defined by using UI or CLI interfaces from the Dell Unity XT platform:

• vVol (Block): A vVol datastore is a block-based storage object that is formatted with the VMware Virtual Volumes (vVol) framework and used to store virtual machine files and metadata. A vVol datastore can be created by using the Unisphere UI or the UEMCLI interface on the Dell Unity XT system. A vVol datastore can provide granular control, policy-based management, and improved performance for virtual machines.
• NFS (File): An NFS datastore is a file-based storage object that is formatted with the Network File System (NFS) protocol and used to store virtual machine files and other data. An NFS datastore can be created by using the Unisphere UI or the UEMCLI interface on the Dell Unity XT system. An NFS datastore can provide scalability, flexibility, and efficiency for virtual machines.
• VMFS (Block): A VMFS datastore is a block-based storage object that is formatted with the VMware File System (VMFS) and used to store virtual machine files and other data. A VMFS datastore can be created by using the Unisphere UI or the UEMCLI interface on the Dell Unity XT system. A VMFS datastore can provide high performance, reliability, and compatibility for virtual machines.

References:

• Dell EMC Unity: VMware ESXi Hosts and Clusters
• Dell EMC Unity: Unisphere Overview
• Dell EMC Unity: Unisphere CLI User Guide

On a Dell Unity XT file system asynchronous replication session, four system Snapshots are required to support replication. Two system Snapshots are created on the source file system, and two system Snapshots are created on the destination file system. The source system Snapshots are used to track the changes that need to be replicated, and the destination system Snapshots are used to apply the changes and maintain a consistent point-in-time copy of the source data. The system Snapshots are automatically created and managed by the replication engine and are not visible to the user.

References: [Dell EMC Unity: Replication Technologies], [Dell EMC Unity: File System Configuration]