Dell PowerVault MD3820f - Manual (Page 30)

Host Server-To-Virtual Disk Mapping
The host server attached to a storage array accesses various virtual disks on the storage array through its
host ports. Specific virtual disk-to-LUN mappings to an individual host server can be defined. In addition,
the host server can be part of a host group that shares access to one or more virtual disks. You can
manually configure a host server-to-virtual disk mapping. When you configure host server-to-virtual disk
mapping, consider these guidelines:
• You can define one host server-to-virtual disk mapping for each virtual disk in the storage array.
• Host server-to-virtual disk mappings are shared between RAID controller modules in the storage
array.
• A unique LUN must be used by a host group or host server to access a virtual disk.
• Not every operating system has the same number of LUNs available for use.
Host Types
A host server is a server that accesses a storage array. Host servers are mapped to the virtual disks and
use one or more iSCSI initiator ports. Host servers have the following attributes:
• Host name — A name that uniquely identifies the host server.
• Host group (used in Cluster solutions only) — Two or more host servers associated together to share
access to the same virtual disks.
NOTE: This host group is a logical entity you can create in the MD Storage Manager. All host
servers in a host group must be running the same operating system.
• Host type — The operating system running on the host server.
Advanced Features
The RAID enclosure supports several advanced features:
• Virtual Disk Snapshots.
• Virtual Disk Copy.
NOTE: The premium features listed above must be activated separately. If you have purchased these
features, an activation card is supplied that contains instructions for enabling this functionality.
Types Of Snapshot Functionality Supported
The following types of virtual disk snapshot premium features are supported on the MD storage array:
• Snapshot Virtual Disks using multiple point-in-time (PiT) groups — This feature also supports snapshot
groups, snapshot images, and consistency groups.
• Snapshot Virtual Disks (Legacy) using a separate repository for each snapshot
For more information, see Premium Feature---Snapshot Virtual Disk and Premium Feature—Snapshot
Virtual Disks (Legacy) .
Snapshot Virtual Disks, Snapshot Images, And Snapshot Groups
A snapshot image is a logical image of the content of an associated base virtual disk created at a specific
point-in-time. This type of image is not directly readable or writable to a host since the snapshot image is
used to save data from the base virtual disk only. To allow the host to access a copy of the data in a
snapshot image, you must create a snapshot virtual disk. This snapshot virtual disk contains its own
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