Free Practice Questions for EMC D-UN-DY-23 Exam

Two ways to create an asynchronous replication session for a NAS server are to use NAS server properties and to use the NAS server wizard. Both methods allow the user to select a source NAS server and a destination NAS server, and configure the replication settings, such as the RPO, the replication schedule, and the replication mode. Creating a replication connection or a replication interface are not ways to create an asynchronous replication session for a NAS server, but rather prerequisites for enabling replication between two Dell Unity systems.

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

Two actions that are recommended according to best practices when connecting iSCSI host to a Dell Unity XT system are to ensure that the interfaces are on separate subnets and to use a private network for iSCSI interfaces. These actions can improve the performance, security, and availability of the iSCSI network. Having interfaces on separate subnets can prevent broadcast storms, reduce network congestion, and enable multipathing. Using a private network for iSCSI interfaces can isolate the iSCSI traffic from other network traffic, reduce the risk of interference or attacks, and simplify the network configuration. Manually registering host on storage array and using standard NIC for iSCSI are not recommended actions, as they can introduce errors, inefficiencies, and limitations.

References: [Dell EMC Unity: iSCSI Configuration], [Dell EMC Unity: Best Practices Guide]

A LUN is a logical unit of storage that is presented to a host as a SCSI device. A LUN is composed of one or more RAID extents, which are the smallest units of storage that can be allocated to a LUN. A RAID extent is a slice of a RAID group that is used to store user data and parity information. The size of a RAID extent depends on the RAID type and the drive type of the RAID group. For example, a RAID 5 extent on a SAS drive is 128 MB, while a RAID 6 extent on a NL-SAS drive is 256 MB. The LUN is partitioned into slices that match the size of the RAID extents, and each slice is mapped to a RAID extent from a RAID group in the storage pool. The LUN slices are distributed across multiple RAID groups to improve performance and availability. References:

Dell EMC Unity: Storage Pools and RAID Groups

Dell EMC Unity: LUN Management

A drive partnership group is a collection of drives of the same drive type that have been combined into a hidden dynamic pool object. Each drive within a dynamic pool can only be part of a single drive partnership group, and a drive will never change the drive partnership group. The maximum size of a drive partnership group is 32 drives, regardless of the drive type or size. When expanding a dynamic pool, the system will automatically create new drive partnership groups as needed, and distribute the drives evenly across the groups. The number of drive partnership groups in a dynamic pool is equal to the number of drives divided by 32, rounded up to the nearest integer. References: Dell Unity: Dynamic Pools2, page 5.

To meet the requirements, the replication connection mode must be set to Both, which allows both synchronous and asynchronous replication sessions to be configured on the same connection. This way, block resources can use synchronous replication, which ensures zero data loss, and file resources can use asynchronous replication, which allows some data difference on the destination. Setting Unisphere resource filtering to All is not necessary, as it only affects the display of resources in the Unisphere GUI. Setting an RPO of 0 on the synchronous replication sessions is redundant, as synchronous replication always has an RPO of 0. Configuring the replication interfaces on the 4-port mezzanine card is not relevant, as it only affects the performance and availability of the replication network.

References: [Dell EMC Unity: Replication Technologies], [Dell EMC Unity: Unisphere Overview]

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]

A benefit of using vVols is that individual VMs on a datastore can be snapped. vVols are virtual volumes that are stored on a storage array and managed by vSphere. They enable granular control and management of VM storage. With vVols, each VM has its own set of virtual disks that are mapped to corresponding storage objects on the array. This allows the array to perform snapshot operations on individual VMs without affecting other VMs on the same datastore.

References: [Dell EMC Unity: VMware vSphere Virtual Volumes (vVols) Implementation]

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 service task that the administrator should perform to fix the issue with minimal impact is Restart Management Software. This service task restarts the management software on both storage processors without affecting the data services or the host I/O. This can resolve the communication issues between Unisphere and the storage system. Reinitialize, Enable SSH, and Reboot Storage Processor are service tasks that have more impact and risk than Restart Management Software.

References: [Dell EMC Unity: Unisphere Overview], [Dell EMC Unity: Service Tasks]