Apple Xsan 2 - Manual (Page 46)

How should users see available storage?
If you want users working on a project to see a volume dedicated to their work, create
a separate volume for each project. If it’s acceptable for a user to see a folder for his or
her work on a volume with other peoples’ folders, create a single volume and organize
it into project folders.
Workflow considerations
How much file sharing is required by your users’ workflow? For example, if different
users or groups work on the same files, simultaneously or in sequence, store those
files on a single volume to avoid needing to maintain or hand off copies. Xsan uses file
locking to manage shared access to a single copy of the files.
Performance considerations
If your SAN supports an application (such as high resolution video capture and
playback) that requires the fastest possible sustained data transfers, design your SAN
with these performance considerations in mind:
Set up the LUNs (RAID arrays) using a RAID scheme that offers high performance. Â
See “Choose RAID schemes for LUNs” on page 47.
Assign your fastest LUNs to an affinity tag for the application. Assign slower LUNs to
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an affinity tag for less demanding applications.
To increase parallelism, spread LUNs across RAID controllers. Xsan then stripes
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data across the LUNs and benefits from simultaneous transfers through two RAID
controllers.
To increase parallelism for an affinity tag assigned to relatively small LUNs (the size
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of one or a few drive modules), create a slice of similar size across all drives on a
RAID controller instead of creating the LUNs from one or two drive modules.
Spread file transfers across as many drives and RAID controllers as possible. Try
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creating slices across the drives in RAID systems, and then assign these slices to the
same affinity tag.
To increase throughput, connect both ports on client Fibre Channel cards to the fabric.
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Store file system metadata on a separate storage pool from user data and make sure Â
the metadata LUNs aren’t on the same RAID controller as user data LUNs.
You can use a separate storage pool for journal data when you create a new volume.
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This significantly improves performance for some operations, such as creating and
deleting files.
Use a second Ethernet network (including a second Ethernet port for each SAN
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computer) for SAN metadata.
If your SAN uses directory services, mail services, or other services on a separate
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server, connect SAN computers to that server on an Ethernet network separate from
the SAN metadata network.
46 Chapter 3 Plan a SAN