NS0-162 Exam Dumps : NetApp Certified Data Administrator (ONTAP)

The space guarantee setting determines how much space is reserved in the aggregate for the volume. A space guarantee of “none” means that no space is reserved for the volume, and the volume can use any available space in the aggregate. This approach to space management is called thin provisioning. This setting would prevent the hosting aggregates from showing a decrease in available space when creating new volumes, as long as the aggregate is not overcommitted. References :- How volume guarantees work with FlexVol volumes, How you set space guarantees for new or existing volumes, What is the impact of changing volume space-guarantee from “volume” to “none”?

The security method that would be used to authenticate targets and initiators in an ISCSI environment is CHAP. CHAP stands for Challenge Handshake Authentication Protocol, and it is a method that validates the identity of targets and initiators during the initial link. CHAP uses a shared secret (a password) that is exchanged between the target and the initiator in a challenge-response manner. CHAP can be used in both one-way and mutual modes, depending on whether both parties need to authenticate each other or not. The other options are not valid for this scenario because:

• NIS is a network information service that provides centralized management of user accounts and host names, but it does not provide authentication for ISCSI devices.
• LDAP is a protocol for accessing and managing directory services, such as user and group information, but it does not provide authentication for ISCSI devices.
• /etc/hosts is a file that maps host names to IP addresses, but it does not provide authentication for ISCSI devices. References :- How iSCSI authentication works, Securing iSCSI Devices, Configure iSCSI authentication

The space allocation option is a LUN attribute that enables the host to communicate with the storage system about the blocks that are no longer in use by the host file system. When the space allocation option is enabled, the host sends SCSI UNMAP commands to the storage system when files are deleted on the disk. The storage system then reclaims the space from the thin-provisioned LUN and makes it available for other LUNs or volumes. This process is also known as space reclamation or hole punching. If the space allocation option is disabled, the host does not send SCSI UNMAP commands and the storage system does not reclaim the space from the thin-provisioned LUN, resulting in a discrepancy between the host and the storage system. References :- Space reclamation, Enable or disable the space allocation option for a LUN