Hardware Installation and User’s Guide
25
Hardware Specifications and Features
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 ICP RAID Console menu
Advanced Setup > Configure Controller > Controller Settings.
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 GDT8514RZ and GDT8114RZ controllers 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 GDT8514RZ and
GDT8114RZ controllers is the
physical drive
limit divided by two. A RAID array drive
may have more than one host drive, but a host drive is always part of just one array drive.
There is a maximum limitation of
30
host drives
per 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
.
Disconnect
Enabled /
Disabled
Automatic
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.
Tagged
Queues
On / Off
Automatic
When enabled, this feature allows the SCSI disk
drive to execute more than one command at a
time.
Disk Read
and Write
Cache
On / Off
Configurable
For performance reasons, the
Read Ahead and
Write cache of the hard disk drives should always
be on. This is the default setting.
Table 3-4. Configurable Disk Drive SCSI Parameters
Table 3-5. Configurable I/O Controller SCSI Parameters
Parameter
Setting/Value
Description
Domain Validation
On / Off
When this is set to
On, Domain validation allows for a check
of the correct data transfer at a given rate for the respective
channel.
