Dot Hill Systems RAIDCore, Руководство пользователя

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18 Chapter 2 Getting Started
Fault tolerance The following fault tolerance features are available with
RAIDCore, in order to prevent data loss in case of a failed disk.
• Disk failure detection (automatic).
• Array rebuild using hot spares (automatic, if the hot spare is
configured for this functionality).
• Parity generation and checking (RAID 5 only).
• Hot-swap manual replacement of a disk without rebooting the
system (available only for systems with a backplane that
supports hot-swapping).
For example if a disk fails in RAID 10, the array remains functional
and data is read from the surviving mirrored disk(s). Up to two disk
failures can be sustained, depending on how the mirrored pairs fail.
Mirror rebuilding A broken mirror can be rebuilt after a new disk is inserted and the
disk is designated as a spare. The system does not have to be
rebooted.
Mirror splitting A mirrored array can be split, so that the volumes can be used
independently.
NOTE:
This feature is available only with RAIDCore
VST. See Split Mirrored Arrays (supported only by
RAIDCore VST) on page 90.
Multiple RAID levels per disk Support for multiple array levels per disk allows the administrator
to create arrays of different RAID levels using the same disks.
Native Command Queuing (NCQ) Native Command Queuing is a command protocol of disks that are
supported by RAIDCore. NCQ enables individual disks to
internally optimize the order in which Read and Write commands
are executed. RAIDCore permits a queue depth of up to 32
read/write commands per disk.
Online Capacity Expansion (OCE) OCE is a process that allows the user to add storage capacity to an
existing array, without taking the system offline. OCE enables the
user to increase the total storage capacity of an array by integrating
unused storage into the array.
Data can be accessed while the disks are added and while data on
the array is being redistributed.
NOTE:
This feature is available only with RAIDCore
VST. See Expanding Disk Capacity Online: Using OCE
(supported only by RAIDCore VST) on page 26.
Table 3 Features of RAIDCore (continued)
RAIDCore Feature Description