HP ProLiant DL280 Configuring Arrays on HP Smart Array Controllers Reference G - Page 67

Changing the controller cache ratio, Enabling or disabling the drive cache

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Syntax: modify reenable [forced] Example command: => ctrl slot=3 ld 1 modify reenable forced Changing the controller cache ratio The controller cache ratio setting determines the amount of memory allocated to read and write operations. Different types of applications have different optimum settings. You can change the ratio only if the controller has a battery-backed cache (because only battery-backed cache can be used for write cache) and if there are logical drives configured on the controller. Syntax: modify cr=#/#|? where is a controller, and #/# is the cache ratio in the format read percentage/write percentage. Example command: => ctrl slot=3 modify cr=25/75 Enabling or disabling the drive cache On controllers and drives that support physical drive write cache, you can use this command to enable or disable the write cache for all drives on the controller. CAUTION: Because physical drive write cache is not battery-backed, you could lose data if a power failure occurs during a write process. To minimize this possibility, use a backup power supply. Syntax: modify drivewritecache=enable|disable|? [forced] where is a controller that supports drive write cache. Example command: => ctrl slot=5 modify dwc=enable Enabling or disabling the array accelerator If the controller has an array accelerator, you can disable or enable it for specified logical drives. NOTE: Disabling the array accelerator for a logical drive reserves use of the accelerator cache for other logical drives on the array. This feature is useful if you want the other logical drives to have the maximum possible performance (for example, if the logical drives contain database information). Syntax: modify aa=enable|disable|? where is a logical drive. Example command: => ctrl slot=3 ld 1 modify aa=enable HP Array Configuration Utility 67

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HP Array Configuration Utility
67
Syntax:
<target> modify reenable [forced]
Example command:
=> ctrl slot=3 ld 1 modify reenable forced
Changing the controller cache ratio
The controller cache ratio setting determines the amount of memory allocated to read and write operations.
Different types of applications have different optimum settings. You can change the ratio only if the controller
has a battery-backed cache (because only battery-backed cache can be used for write cache) and if there
are logical drives configured on the controller.
Syntax:
<target> modify cr=#/#|?
where
<target>
is a controller, and
#/#
is the cache ratio in the format
read percentage/write
percentage.
Example command:
=> ctrl slot=3 modify cr=25/75
Enabling or disabling the drive cache
On controllers and drives that support physical drive write cache, you can use this command to enable or
disable the write cache for all drives on the controller.
CAUTION:
Because physical drive write cache is not battery-backed, you could lose data if a
power failure occurs during a write process. To minimize this possibility, use a backup power
supply.
Syntax:
<target> modify drivewritecache=enable|disable|? [forced]
where
<target>
is a controller that supports drive write cache.
Example command:
=> ctrl slot=5 modify dwc=enable
Enabling or disabling the array accelerator
If the controller has an array accelerator, you can disable or enable it for specified logical drives.
NOTE:
Disabling the array accelerator for a logical drive reserves use of the accelerator cache
for other logical drives on the array. This feature is useful if you want the other logical drives to
have the maximum possible performance (for example, if the logical drives contain database
information).
Syntax:
<target> modify aa=enable|disable|?
where
<target>
is a logical drive.
Example command:
=> ctrl slot=3 ld 1 modify aa=enable