HP D5970A - NetServer - LCII Configuration Manual page 133

RAID levels 10, 30, and 50 result when logical drives span arrays. Table 2-2 in
Chapter 2 describes RAID levels for logical drives that span arrays.
RAID 10 results when a RAID 1 logical drive spans arrays.
RAID 30 results when a RAID 3 logical drive spans arrays.
RAID 50 results when a RAID 5 logical drive spans arrays.
Read Policy: The three Read policies for HP NetRAID are:
Read-Ahead: This is a memory caching ability that tells the controller to
read sequentially ahead of requested data and cache the further data in
memory, anticipating that the further data will be requested. Read-Ahead
supplies sequential data faster, but is not as effective when accessing
random data.
Normal: This policy does not use the read-ahead memory caching feature.
This policy is efficient when most of the data reads are random.
Adaptive: Adaptive policy causes the read-ahead feature to be used if the
last two disk accesses were in sequential sectors.
Ready State: A condition in which a workable hard drive is neither online nor a
hot spare, and therefore is available to add to an array, or to designate as a hot
spare.
Rebuild: The regeneration of all data from a failed disk in a RAID level 1, 3, 5,
10, 30, or 50 array to a replacement disk. A disk rebuild normally occurs without
interruption of application access to data stored on the logical drive.
Rebuild Rate: The speed at which the rebuild operation proceeds. Each
controller is assigned a rebuild rate, which specifies the percentage of IOP
resources to be devoted to rebuild operations.
Reconstruct: The act of remaking a logical drive after changing RAID levels.
Redundancy: See RAID Levels
SCSI Channel: The integrated HP NetRAID controller controls the disk drives
via SCSI-2 buses called "channels" over which the system transfers data in Fast-
and-Wide, Ultra SCSI, or Ultra2 SCSI mode. An integrated HP NetRAID
controller can manage one or two SCSI channels.
SCSI Disk Status: A SCSI disk module (physical drive) can be in one of five
states:
Ready: a powered-on and operational disk that has not been configured.
Glossary
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