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]

To apply the management IP from the vSphere UnityVSA console, the system administrator must use the svc_initial_config command. This command allows the user to configure the initial network settings for the UnityVSA, such as the management IP address, subnet mask, gateway, and DNS servers. The svc_ipmi command is used to configure the IPMI settings for the UnityVSA, such as the IPMI IP address, username, and password. The svc_change_hw_config command is used to change the hardware configuration of the UnityVSA, such as the number of CPU cores, memory size, and disk size. The svc_inject command is used to inject faults into the UnityVSA for testing purposes.

References: [Dell EMC UnityVSA Installation Guide], [Dell EMC UnityVSA Command Line Interface Reference Guide]

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]

When the Schedule Time Zone is changed under the Settings menu, it only affects the display of the time zone and the creation of new snapshot schedules. Existing snapshot schedules are not automatically adjusted to the new time zone, and will continue to run at the same absolute time as before. For example, if a snapshot schedule was created to run every day at 10:00 AM inGMT+1, and the Schedule Time Zone was changed to GMT+2, the snapshot schedule will still run at 10:00 AM in GMT+1, which is 11:00 AM in GMT+2. To update the existing snapshot schedules to the new time zone, the administrator must edit each schedule manually and change the start time accordingly. References: Dell EMC Unity: Snapshots and Thin Clones1, page 16.

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

 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.

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]