Apple Xsan 2 - Manual (Page 67)

Chapter 4 Set up a SAN 67
4 In the Configure Volume Affinities pane (or the Configure Volume Storage pane, if
you’re configuring a custom volume type), drag LUNs from the left column to the
corresponding affinity tag (or custom storage pool) in the right column.
a Drag the special metadata LUN you created (in Step 6, “Create a Metadata Array”) to
the MetadataAndJournal affinity tag (or custom storage pool).
b Drag your other LUNs to the other affinity tags (or storage pools). To avoid wasting
storage, all LUNs assigned to an affinity tag (or storage pool) should be the same size.
c When you finish, click Continue.
For information about the optimal number of LUNs to assign to an affinity tag, see
“Assign LUNs to affinity tags” on page 48.
5 Optionally, you can select an affinity tag and click Settings to change the affinity tag
name or other settings listed below. If you’re creating a custom volume, you can select
it and click Storage Pool Settings to change the storage pool name or other settings
listed below.
Affinity Tag (or Storage Pool Name): Enter the name for the affinity tag (or custom
storage pool). If the OK button is disabled when you finish entering the name, the
name is reserved; try another. For more information about reserved names, see “If you
can’t add a storage pool” on page 124.
Use for: Choose the types of data that can be stored on storage pools that have this
affinity tag (or that can be stored on the custom storage pool), following these rules:
The first affinity in a volume can allow metadata only, journaling and metadata, or any
data (which includes metadata, journaling, and user data). Thus the first affinity must
always allow metadata.
Other affinities can allow any data, only journaling and metadata, only journaling, only
metadata, or only user data.
Only one affinity can allow journaling.
You can’t change the type of data an affinity stores without recreating the volume.
If you allow user data only, you can specify whether to allow only data that has
the matching affinity. If the data must have the matching affinity, the tag is called
“exclusive,” and data without the affinity isn’t allowed. You can change this setting as
needed. However, a volume must contain at least one affinity tag that isn’t exclusive. In
other words, the volume must contain at least one affinity tag that accepts user data
without an affinity.
Stripe Breadth: Specify how much data is written to or read from each LUN in storage
pools that have this affinity tag (or each LUN in the custom storage pool) before
moving to the next LUN. This value can affect performance. If you’re not sure what
value to use, accept the preset value.