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6
Adaptive Path Optimization (ExpressSAS RAID only)
Often users need redundancy and improved performance. This can be achieved using dual SAS domains via
adaptive path optimization. In this configuration, multiple physical connections to drives are created to eliminate
pathway failure concerns (i.e. external cable failure, expander failure, RAID controller failure, or failure in a
spanned JBOD configuration), as well as to distribute data movement over all available connections to maximize
performance. To take advantage of multiple domains, devices must be dual-ported and cabled properly.
1
In a standard configuration, a single cable is
connected to a storage array (see
for basic connectivity. As an alternative, most
SAS/SATA storage arrays have a second
connector for daisy chaining additional storage.
This connector may also be used to provide a
redundant connection from your ATTO
ExpressSAS RAID adapter (see
This eliminates a single point of failure between
the adapter and storage and may also provide
a performance improvement. As a third option,
SAS drives have two connections to each drive
that can be used to provide even more options
for improved performance and redundancy. To
take advantage of this option, connect a cable
from your ExpressSAS RAID adapter to each
expander port on your storage array (see
Exhibit
6-1).
Exhibit 6-1
Exhibit 6-2
30 ATTO Technology Inc. ATTO ExpressSAS Host & RAID Adapter Installation and Operation Manual
Exhibit 6-3
Exhibit
6-1)
Exhibit
6-1).
2
Adaptive path optimization occurs when
multiple paths to a drive are available. It
automatically configures primary and alternate
paths for highest levels of redundancy, as well
as highest data transfer rates. Using event-
driven algorithms, it evaluates and adaptively
re-configures data path assignments for
optimal performance. No user intervention is
required for this feature. For the cost of a cable,
you get:
• Automatic configuration
• Redundancy and improved performance
• Path matching that is RAID Group aware
• Automatic and balanced failover/failover
• Stable configurations
Note
Refer to documentation from your storage
array vendor for additional information on
cabling to your particular array.
capabilities.
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