3-31
Installing the DuraStor Storage Subsystem
Important Information About SAN Environments
In configurations where there are multiple paths from the host
server to the DuraStor, each partition (defined as a FC LUN) is
presented to the host as many times as there are paths. For
example, if there are two paths from the host to the DuraStor, each
partition is seen by the host two times; if there are four paths, each
partition is seen four times, and so on. See
Figure 3-27
through
Figure 3-30
for examples.
To prevent the operating system on the host from being confused
by the redundant instances of each partition, they must be
masked
out by using an FC HBA that offers LUN masking. This feature
hides the redundant instances of each partition from the operating
system on the host server until the
primary
path fails.
Caution:
In a multi-path SAN environment, you must use
FC HBAs that offer LUN masking; otherwise, the host
operating system will see the redundant instances of each
partition. If the host operating system attempts to write to
the redundant instances of the same partition on the
DuraStor, it will likely cause data corruption or loss.
Figure 3-27 Two Data Paths - Example A
Figure 3-28 Two Data Paths - Example B
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DuraStor IUG.book Page 31 Wednesday, January 30, 2002 10:49 AM
