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An important part of effectively maintaining a storage infrastructure
depends on how accessible and secure the data is at all times. With LUN
filtering support, SANscape provides a utility for secure centralized
storage access management. For multiple servers connected to the same array, LUN filtering provides
an exclusive path from a server to a logical drive and essentially hides
or excludes the other connected servers from seeing or accessing the same
logical drive. That is, the LUN filter organizes how the array devices
are accessed and viewed from host devices, and typically maps an array
device to only one host so that the other hosts do not access and use
the same array device. LUN filtering also enables multiple logical drives
or partitions to be mapped to the same LUN number enabling different servers
to have their own LUN 0 to boot from if needed. LUN filtering is also
valuable in clarifying mapping when each HBA typically sees twice the
number of logical drives when viewed through a hub. Each Fibre Channel device is assigned a unique identifier called a worldwide
name (WWN). A WWN is assigned by the IEEE and is similar to a MAC address
in IP or a URL on the Internet. These WWNs remain with the device for
its lifetime. LUN filtering uses this WWN to specify which server is to
have exclusive use of a specific logical drive. An easy drag-and-drop
method is used to map each array logical drive to a host's Fibre Channel
HBA card, identified with a WWN. As shown in the following example, when you map LUN 01 to host channel
0 and select WWN1, Server A has a proprietary path to that logical drive.
All servers continue to see and access LUN 02 and LUN 03 unless filters
are created on them. An advantage of LUN filtering is that it allows many more hosts like
Windows NT to attach to an array through a common Fibre Channel port and
still maintain LUN security. |