Data Protection; Raid Levels; Active Spare - HP StorageWorks NAS 8000 - Version 1.6.X Manual

The NAS solution supports two failover models:

Data Protection

RAID Levels

Redundant Array of Inexpensive Disks (RAID) technology uses different industry-standard
techniques for storing data and maintaining data redundancy. These techniques, called "RAID
levels," define the method used for distributing data on the disks in a logical unit (LUN). The
storage arrays used in the NAS 8000 solution support the following RAID levels:
Note:
For additional information on RAID settings, see your storage array user's guide or search for
RAID levels at http://www.hp.com.

Active Spare

The active spare feature in the storage array offers increased protection against disk failure. An
active spare ensures that the array can restore data redundancy and performance as quickly as
possible following a hard disk failure.
An active spare reserves capacity to perform a rebuild in the event of a disk failure. If you are
using disks of different capacities in your array, active spare reserves enough space to rebuild
the largest disk. As with logical volumes, the capacity reserved for the active spare is
distributed across all the disks in the array; no one physical disk contains the active spare.
HP StorageWorks NAS 8000 SAN High Availability, Solution Integration Manual (SIM)
Active/Active (or "Dual Active") means that both cluster nodes can be serving data
simultaneously. The nodes provide failover services for each other, but can be fully
utilized at all times. This mode is achieved by configuring failover packages to run on both
cluster nodes – effectively dividing the storage between the nodes.
Active/Passive (or "Single Active") means that one node is actively serving data while the
other node is in full-time stand-by mode, becoming active only when the other node fails.
This mode can be realized by configuring all of the failover packages and storage to run on
only one node. Without any failover packages to run, the other node waits and monitors
the other node for failure.
RAID 1+0. RAID 1+0 provides data redundancy and good performance. However, the
performance is achieved by using a less efficient technique of storing redundant data
called "mirroring." Mirroring maintains two sets of the data: a primary set and a backup
set, or "mirror," of the primary set. Therefore, half of the disk space is consumed by
redundant data.
AutoRAID. AutoRAID is a combination of RAID 1+0 and 5DP (RAID 5 Double Parity).
RAID 5DP provides data redundancy and improves cost-efficiency by using a more
efficient method of storing redundant data. However, there is a performance penalty for
each write operation.
AutoRAID relieves you of many of the decisions regarding RAID levels and data location
by automatically selecting RAID 1+0 or RAID 5DP depending on the usage patterns of
the data. AutoRAID automatically manages your data for you, providing redundancy and
high performance with minimal involvement. This configuration eliminates the
requirement for the system administrator to understand and configure RAID levels.
The information for AutoRAID presented here applies to VA arrays only.
Network and Storage Planning
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