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Table 3-4. Configurable Disk Drive SCSI Parameters
Disconnect
Tagged
Queues
Disk Read
and Write
Cache
3.5.3
Configurable I/O Controller SCSI Parameters
When the controller starts up, its SCSI parameters are automatically set to their optimal
settings. Manual configuration is not required. However, you can customize I/O SCSI
parameters for each channel on the controller by using the Storage Console menu
Advanced Setup > Configure Controller > Controller Settings.
Table 3-5. Configurable I/O Controller SCSI Parameters
Parameter
Domain Validation
3.6
RAID Controller Drive Limitations (Host, Array,
Logical, and Physical)
The following are limitations assuming the following:
•
U320 speed hard disk drives
•
Dual channel SCSI controller
•
Cabling that meets U320 specifications
Physical drives are limited by the number of SCSI channels being controlled by the RAID
controller. The firmware/software supports a maximum of 15 hard disk drives per channel
(or 14 if one SCSI ID is being occupied by an intelligent enclosure processor).
The maximum number of array drives is limited by the RAID firmware. The actual limit
of the SRCU42L controller is 15 array drives per dual-channel controller. A RAID array
drive requires a minimum of two hard disk drives (or logical drives). Therefore the
maximum RAID array drive limitation for the SRCU42L controller is the physical drive
limit divided by two. A RAID array drive can contain (or have reside on it) up to a
maximum of 2 host drives.
There is a maximum limitation of 30 host drives per SRCU42L controller. There is a
minimum of at least one host drive per array drive. A host drive can only be associated
with (or reside on) a single array drive.
Hardware Installation and User's Guide
Enabled /
Automatic
Disabled
On / Off
Automatic
On / Off
Configurable
Setting/Value
When this is set to On , Domain validation allows for a
On / Off
cyclical check of the correct data transfer at a given rate for
the respective channel.
Hardware Specifications and Features
Enabling this setting allows for the disk drive to
disconnect from the SCSI bus when it's not
participating in a transfer. This allows for optimal
bus utilization by all devices on the bus.
When enabled, this feature allows the SCSI disk
drive to execute more than one command at a
time.
For performance reasons, the Read Ahead and
Write cache of the hard disk drives should always
be on. This is the default setting.
Description
27
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