Apple Xsan 1.4 - Manual (Page 50)

50 Chapter 2 Setting Up a Storage Area Network
Estimating Metadata and Journal Data Storage Needs
To estimate the amount of space required for Xsan volume metadata, assume that
10 million files on a volume require approximately 10 gigabytes of metadata on the
volume’s metadata storage pool.
Choosing an Allocation Strategy
The allocation strategy you choose for a volume determines the order in which its
storage pools are filled with data. You can choose round robin, fill, or balance.
If you choose round robin, Xsan writes new data in turn to each storage pool in
the volume.
If you choose fill, Xsan writes all new data to the first storage pool in the volume until
that storage pool is full, and then moves to the next storage pool. This is a good choice
if you want to keep a particular storage pool unused as long as possible.
If you choose balance, Xsan writes new data to the storage pool with the most
free space.
Connecting Computers and Storage Devices
Before you set up your Xsan SAN, connect client computers, controller computers, and
storage devices to the SAN’s Fibre Channel and Ethernet networks. Make sure your
networks meet the requirements summarized under “Fibre Channel Fabric” on page 35
and “Ethernet TCP/IP Network” on page 36.