Apple Xsan 1.4 - Manual (Page 94)

94 Chapter 3 Managing SAN Storage
For Xserve RAID systems, which have an optimal transfer size of 1 MB, this becomes:
stripe breadth = 1048576 / block allocation size
If, for example, you are using an application such as Final Cut Pro to move large
amounts of video data, choose the largest block allocation size (512KB) and use the
equation to find the stripe breadth of 2 blocks. Then, Xsan writes 1 MB of data (two
512KB blocks), in turn, to each LUN in your video storage pool.
Setting the Selection Method for Multiple Connections
If there is more than one Fibre Channel connection to the LUNs in a storage pool, you
can choose whether Xsan alternates between connections for each write or statically
assigns each LUN in the volume to a connection at volume mount time. This is called
the “multipath method.”
To change the multipath method:
1 In Xsan Admin, select the SAN that the storage pool belongs to, click Setup, and click
Storage.
2 Double-click the storage pool in the list.
3 Choose a value from the Multipath Method pop-up menu.
 Static: Xsan assigns each LUN in a storage pool to one of the connections when the
volume is mounted.
 Rotate: Xsan switches to a different connection each time it writes data to the
storage pool. This can improve performance.
4 Click OK, and then click Save.