DEC DS-HSZ22-AA, Руководство пользователя

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Chapter 2. RAID Array Controller
EK–SMCPO–UG. A01 2–19
Table 2–6 System Parameters
Parameter Description
Password Checking Enables or disables password checking. When password checking
is enabled, the controller will limit access to certain options unless
the correct password is supplied.
Rebuild Rate Determines how much of the controller’s processing power is to be
used during rebuild operations. A higher number speeds up the
rebuild operation, but may impact I/O performance. A lower num-
ber will not impact performance, but will require longer to rebuild
the RAID set.
Create Rate Similar to Rebuild Rate, but determines the amount of processing
power to be used while creating a RAID set.
UPS Installed Determines whether the controller should enable the UPS warning
signals (AC Lost and Two-Minute Warning). See “Backup Power
Management” for more details.
Read-Ahead Enabled Determines whether the controller should automatically pre-stage
data into cache during read operations. Enabling read ahead im-
proves sequential access times as it improves the chance of get-
ting a cache hit on a read. However, it is not well suited for random
access patterns since it relies on spatial locality.
Read-Ahead Limit Limits the amount of cache blocks that will be read ahead when
read ahead is enabled. This limit prevents the cache from being
dominated by read-ahead data.
Validation Delay Determines how long the controller will delay after spinning up
drives before scanning them. The larger the number, the more time
the drives have to initialize themselves.
12-Volt Sensor Enabled Determines whether the controller should monitor the 12-volt input
line.
Host Select WCE Specifies whether the controller allows the host to set and/or clear
the Write Cache Enable bit in the caching mode page. Prevents
host systems from turning write caching off and degrading per-
formance. See “Write Operations” for more details.
Drive Command Time-out The number of seconds the controller will wait for a drive to re-
select after disconnecting during the processing of a command. If a
drive exceeds this time, the command will be retried. This value
also indicates the maximum amount of time a drive can be on the
SCSI bus. If a drive is on the bus for a greater length of time, the
drive will be reset and the command will be retried.
Reset Propagation Specifies whether the host channels should propagate resets on
other host channels. This is useful in clustering environments
where one cluster may need to silence the adapter of a failing peer
cluster.