Public alias
This is a symbolic name that you can assign to a
target on the . The public alias is seen by some
iSCSI initiators; it can help you identify the
iSCSI target. The public alias for a storage pool’s
default target is the pool name. You can change
a target’s public alias at any time.
R
RAID 10
RAID 10 provides very high performance and
redundancy. In a RAID 10 implementation, data
is simultaneously mirrored and striped. RAID 10
can, under certain circumstances, support
multiple drive failures. It is ideally suited for
situations where both high performance and
redundancy are important. RAID 10
implementation on has some unique
requirements, and please refer to "Understanding
storage pools, volumes, and storage
enclosures".
RAID 5
RAID 5 provides redundancy by writing data and
parity information across three or more drives,
thereby increasing performance. You need at
least 3 disk drives for a RAID 5 implementation.
RAID 5 can withstand a single disk failure
without losing data or access to data. It is ideally
suited for transaction processing, database
applications, file and print servers.
RAID 6
RAID 6 is similar to RAID 5, but with better fault
tolerance. RAID 6 stripes blocks of data and
parity across an array of drives like RAID 5,
except that it calculates two sets of parity
information for each parcel of data. This
significantly improves fault tolerance: RAID 6
can withstand the failure of any two drives in the
array without losing data or access to data.
RAID 6 is ideally suited for the same
applications as RAID 5, but in situations where
additional fault tolerance is required. We
recommend adding Nexsan FASTier cache
devices to a RAID 6 implementation to improve
write performance.
Random-access memory (RAM)
A memory chip that allows stored data to be
accessed at any time in any order. Commonly
used in computers as main operating memory.
Values in randomaccess memory are often
volatile; information is lost if power is removed
from the module.
Read-only memory (ROM)
A memory chip that stores values but cannot be
changed by normal program instructions. Values
in read-only memory are nonvolatile; they are
retained even when the unit is powered down.
Remote
In asynchronous replication, a remote or
secondary site represents the system to which
data from the primary is replicated. In a
deployment where asynchronous replication is
not implemented, a remote represents a site that
is being managed remotely from another or site.
Replica
A duplicate of a file system on a Nexsan copied
onto another Nexsan . At the time of replication,
replicas contain all of the data on the original
volume. Replicas can be promoted to full file
systems, after which replication between the two
file systems is no longer possible.
Replication
A function of Nexsan s that allows the user to
make replicas of a volume onto another Nexsan
to protect data in the event of a disaster, or as
part of a backup and restore architecture.
S
SAN
(Storage area network) An architecture that
provides for attachment of remote computer
storage devices to servers in such a way that the
devices appear as locally attached to the
operating system.
SAS
(Serial Attached SCSI) A serial version of the
SCSI interface. A point-to-point architecture that
Glossary
Nexsan Unity Hardware Reference Guide
www.nexsan.com
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