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LUN Filtering Overview (Fibre Channel and SATA Only)

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.

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. WIth LUN filtering, the logical drive is visible and accessible to only the HBA device on the host, but not to any other HBA device. All three servers continue to see and access LUN 02 and LUN 03 unless filters are assigned to them.

Diagram showing multiple hosts with access to the same LUNs where LUN filtering creates 
exclusive paths from a server to a specific LUN.

An advantage of LUN filtering is that it enables many more hosts, with multiple OSs, to attach to an array through a common Fibre Channel port and still maintain LUN security.

For details on LUN filtering, see Assigning a LUN Filter.

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