Specifying Logical Drive Properties

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Use the Logical Drive Properties dialog to specify the modification priority , cache properties, and media scan properties of a selected logical drive. Also, you can view the progress of a logical drive modification operation on this dialog.

How to Access the Logical Drive Properties Dialog

To access the Logical Drive Properties dialog, select a logical drive in the Logical View; then, select either the Logical Drive >> Properties pull-down menu option, or Properties from the right-mouse pop-up menu.

Result: The Logical Drive Properties dialog is displayed.

Viewing Base Properties Information

The Base tab of the Logical Drive Properties dialog displays the following logical drive data: logical drive name, world wide name , status, capacity, RAID level, and segment size.

Setting Modification Priority

To set the modification priority, click and hold the settings button on the slider bar and move it to the desired priority. For more information about logical drive modification priority, see Learn About Logical Drive Modification Priority and Performance.

Viewing the Progress of a Modification Operation

The progress bar at the bottom of the Logical Drive Properties dialog displays the progress of an operation.

You can view the progress of the following operations:

* The Progress Bar label shows "Modification progress" rather than the operation name.

Important: The storage management software cannot obtain progress information from the storage subsystem controllers if the network management connection to the controllers is down or if the storage subsystem is partially managed. In either case, the progress bar on the dialog displays "zero percent complete" and the text above the progress bar displays "<operation> progress data unavailable." For more information on a partially managed storage subsystem or an Unresponsive controller or storage subsystem condition, see the Enterprise Management Window help system.

Setting Cache Properties

Use the Cache Properties tab to enable or set the following cache parameters.

Note: In certain situations, the controller may temporarily suspend caching operations when caching is not appropriate. This status is called Enabled but Not Active.

Cache Parameter

Description

Read Caching

Allows read operations from the host to be stored in controller cache memory.

If a host requests data that is not in the cache, the controller reads the needed data blocks from the disk and then places them in the cache. Until the cache is flushed, all other requests for this data are fulfilled with cache data rather than from a physical disk read, increasing throughput.

To enable the read caching parameter, select the Read Caching checkbox.

Write Caching

Allows write operations from the host to be stored in cache memory.

The logical drive data in the cache is written to disk, or flushed, automatically at the interval you specify in the Flush write caching after parameter.

Note: There also are cache settings you can set at the storage subsystem level that affect all logical drives. Select Storage Subsystem >> Change Cache Settings. For more information, see Specifying Storage Subsystem Cache Settings.

To enable the write caching parameter, select the Write Caching checkbox.

Write cache mirroring

Allows cached data to be mirrored across redundant controllers with the same cache size. Data written to the cache memory of one controller is also written to the cache memory of the other controller. Therefore, if one controller fails, the other can complete all outstanding write operations.

Important: To use this option:

  • You must be using an active/active controller pair.
  • Both controllers must have the same size cache. To check controller cache size, select the controller in the Physical View; then, select either the Controller >> Properties pull-down menu option, or Properties from the right-mouse pop-up menu.

To enable the write cache mirroring parameter, select the Write Cache Mirroring checkbox.

Note: This option is available only when write caching is also enabled.

Write caching without batteries

Allows write caching to continue, even if the controller batteries are discharged completely, not fully charged, or not present. If you select this parameter without a back-up power supply, you could lose data if power fails.

Enable the Write Caching Without Batteries parameter by selecting the checkbox.

Note: This option is only available if write caching is also enabled.

Cache read-ahead multiplier

Cache read-ahead lets the controller copy additional data blocks into the cache while it is reading and copying host-requested data blocks from disk into the cache. This increases the chance that a future request for data could be fulfilled from the cache. Cache read-ahead is important for multimedia applications that use sequential I/O.

The cache read-ahead multiplier values specify the multiplier to use to determine how many additional data blocks are read into cache. A higher cache read-ahead multiplier may increase the cache hit percentage. However, transfer time might increase also.

In the cache read-ahead multiplier spinner box, choose a multiplier.

Disabling cache read-ahead

To disable cache read-ahead, select 0 in the cache read-ahead multiplier spinner box.

Enabling a Background Media Scan

To enable a background media scan for this logical drive, select the Enable background scan check box.

Enabling a Redundancy Check

During a redundancy check, all data blocks in a logical drive are scanned, and:

Note: RAID 0 logical drives have no data redundancy.

Select the With redundancy check radio button to enable a redundancy check during a media scan.

Applying Individual Logical Drive Properties to All Logical Drives

To apply all settings of an individual logical drive (modification priority, cache, and media scan) to all other logical drives in the storage subsystem, click the Apply Settings to All Logical Drives checkbox. Use this checkbox only if you want all logical drives in the storage subsystem to share the same settings. This option overwrites any current settings on the other logical drives in the storage subsystem.

Related Topics

Learn About Logical Drive Modification Priority and Performance

Learn About Cache Memory Protection

Learn About Cache Settings and Performance

Specifying Storage Subsystem Cache Settings

Learn About the Background Media Scan Process