Gateway E-842R, User Manual

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Manually configuring a storage solution www.gateway.com
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Initialization RAID 5/50 arrays must have consistent parity before they can be
used to protect data. Initialization writes a known pattern to all
drives in the array. If you choose not to initialize an array, the array
is trusted. Any drive failure results in data corruption in a trusted
array. (You can later perform a parity rewrite, which recalculates
the parity based on the current data, thus ensuring the data and
parity are consistent.)
Logical Drive Availability To accommodate hosts with multiple ports and multiple host
systems, you can restrict a logical drive’s availability to a particular
HBA or controller port. Access can be enabled or disabled for each
host port of each controller.
Mapped LUN Number Each logical drive is presented to the host system with a unique
LUN. In certain cases (such as after deleting another logical drive)
you may want to change the number that a logical drive is
assigned. You can do this at any time, but any attached host
systems may need to be rebooted or re-configured to maintain
access to the logical drive.
RAID Level 0 RAID 0 is defined as disk striping where data is striped or spread
across one or more drives in parallel. RAID 0 is ideal for
environments in which performance (read and write) is more
important than fault tolerance or you need the maximum amount
of available drive capacity in one volume. Drive parallelism
increases throughput because all disks in the stripe set work
together on every I/O operation. For greatest efficiency, all drives
in the stripe set must be the same capacity. Because all drives are
used in every operation, RAID 0 allows for single-threaded, I/O
only (only one I/O operation at a time). Environments with many
small simultaneous transactions (such as, order entry systems) do
not get the best possible throughput.
RAID Level 1 RAID 1 is defined as disk mirroring where one drive is an exact
copy of the other. RAID 1 is useful for building a fault-tolerant
system or data volume and provides excellent availability without
sacrificing performance. However, you lose 50 percent of the
assigned disk capacity. Read performance is somewhat higher
than write performance.
RAID Level 5 RAID 5 is defined as disk striping with parity where the parity data
is distributed across all drives in the volume. Normal data and
parity data are written to drives in the stripe set in a round-robin
algorithm. RAID 5 is multi-threaded for both reads and writes
because both normal data and parity data are distributed
round-robin. This is one reason why RAID 5 offers better overall
performance in server applications. Random I/O benefits more
from RAID 5 than does sequential I/O, and writes take a
performance hit because of the parity calculations. RAID 5 is ideal
for database applications.
RAID Level 10 RAID 10 (also known as RAID 0+1) is defined as mirrored stripe
sets. You can build RAID 10 either directly through the RAID
controller (depending on the controller) or by combining software
mirroring and controller striping, or vice versa (called RAID 01).
RAID Level 50 This RAID level is a combination of RAID level 5 and RAID level 0.
Individual smaller RAID 5 arrays are striped, to give a single RAID
50 array. This can increase the performance by letting the
controller more efficiently cluster commands together. Fault
tolerance is also increased so one drive can fail in each individual
array.
Term Description