EMC D-UN-DY-23 Exam With Confidence Using Practice Dumps

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

To expand a dynamic pool, the number of drives added must be equal to or greater than the stripe width of the pool. The stripe width is the number of data drives plus the number of parity drives in a RAID group. In this case, the stripe width is 12 + 1 = 13. Therefore, the minimum number of drives needed for the pool expansion is 13. References: Dell EMC Unity: Dynamic Pools Technical White Paper1, page 8.

A feature that can be configured for a Dell Unity XT file system NFS share is the Host Access Level. This feature allows the user to specify the access permissions for each host or host group that is allowed to access the NFS share. The access permissions can be set to Read/Write, Read Only, or No Access. The Host Access Level feature can be used to control the security and performance of the NFS share. Access-Based Enumeration, Protocol Encryption, and Distributed File System are features that can be configured for a Dell Unity XT file system SMB share, not NFS share.

References: [Dell EMC Unity: File System Configuration], [Dell EMC Unity: SMB Share Configuration]