Apple Xsan 1.4 User Manual

Page 47

Chapter 2

Setting Up a Storage Area Network

Creating storage pools from LUNs that are hosted on different drive modules and

different RAID controllers increases performance by increasing the parallelism of data

transfers. For example, a storage pool consisting of two LUNs, each a single drive

module on the left side of an Xserve RAID, will not be as fast as a similarly sized storage

pool made up of two LUNs that are single slices across all seven drives, one slice on

each controller. In the first case, all transfers go through a single RAID controller to just

two drives; in the second case the same transfer is spread across two RAID controllers

and fourteen drives.

Assigning Storage Pools to Volumes

After you decide how to combine available LUNs into storage pools, assign the storage

pools to the volumes you want to create.

For best performance, create a separate storage pool just for file system metadata and

journal data.

Deciding Which Clients to Mount a Volume On

If you create multiple volumes, decide which volumes should be mounted on which

clients.

Choosing Controllers

You must choose at least one computer to be the SAN controller, the computer that is

responsible for managing file system metadata.

Note: File system metadata and journal data are stored on the SAN volume, not on the