HP NetRAID 1 Controller - Manual (Page 29)

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Check Consistency: Ensures that parity or mirroring is correct for the selected drives. Click
on the drive to be checked (LD0-LD7). RAID levels 1, 3, and 5 use mirroring or parity to
store parity data blocks. Parity or mirroring is checked between these parity data blocks and
the selected drives when you select this option.
Check consistency should be run if the system shuts down irregularly, e.g., if the system
hangs or suffers a power failure. It is also recommended to run consistency checks every 2-4
weeks to ensure that bad blocks on the disk drive are mapped out. (See the “Check
Consistency Feature.”) Check consistency will always remedy inconsistencies. Check
consistency will only fail because firmware could not complete parity and data writes due to a
power-failure or a system hang, or because the logical drive degraded or failed due to the
physical drives going offline.
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Properties: Displays the logical drive properties of the selected logical drive. Each logical
drive can be displayed by selecting the Previous or Next buttons.
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Change Config: Select the logical drive or drives to change, then click on Change Config
and the preferred Change Config option. You must also initialize these drives.
◊ Cache: This parameter specifies read cache mode during data transfers involving the
current logical drive.
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Direct: Direct I/O specifies only repeated reads to same locations are cached.
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Cached: Cached I/O specifies that all reads are cached.
◊ Read: This parameter enables the SCSI Read-Ahead feature for the logical drive.
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Normal: Specifies that the controller does not use Read-Ahead for the current logical
drive.
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Read-Ahead: Specifies that the adapter uses Read-Ahead for the current logical
drive.
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Adaptive Read-Ahead: Specifies that the adapter begins using Read-Ahead if the
two most recent disk accesses occurred in sequential sectors. This is the default
setting.
◊ Write: This parameter sets the cache write policy. You can set the write policy to Write-
Back or Write-Through. Write-Through caching has a data security advantage over
Write-Back caching, whereas Write-Back caching has a performance advantage over
Write-Through caching.
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In Write-Back caching the adapter sends a data transfer completion signal to the host
when the adapter cache has received all the data in a transaction.
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In Write-Through caching, the adapter sends a data transfer completion signal to the
host when the disk subsystem has received all the data in a transaction. Write-Through
is the default setting.
◊ RAID Level: This option allows you to set a valid RAID level.
◊ Add Capacity: Use this option to add capacity to the logical drive.
Logical Drive Right Mouse Button Menus
When the Logical Devices box is set to Logical View, clicking on the right mouse button opens a
quick-access Logical Drive Menu. To access this menu, place the mouse pointer on a logical drive
icon and click the right mouse button. The following popup menu options appear.