Avago Technologies MegaRAID SAS 9341-4i - Manual (Page 13)

Avago Technologies
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MegaRAID SAS Device Driver Installation User Guide
June 2015 Windows Driver Installation
MegaRAID Primary Storage
5. Select a power save mode for the drive group from the Power save mode field.
The options available are Auto, Max, and Controller defined.
This field is enabled only if power saving on configured drives is supported on the controller.
6. Enter a name for the virtual drive in the Name field.
The name given to the virtual drive cannot exceed 15 characters.
7. Press OK.
A dialog appears, asking you whether you want to initialize the virtual drive you just created.
8. To initialize the virtual drive, press OK.
The Create New VD dialog appears again.
9. Press Advanced.
The Create Virtual Drive – Advanced dialog appears. The following are the additional virtual drive properties that
you can select while you create virtual drive. Change these parameters only if you have a specific reason for doing
so. It is usually best to keep them at their default settings.
 Strip Size – The strip size is the portion of the stripe that resides on a single virtual drive in the drive group. Strip
sizes of 64 KB, 128 KB, 256 KB, 512 KB, or 1 MB are supported.
 Read Policy – Specify one of the following options to specify the read policy for this virtual drive:
— Normal – Read ahead capability lets the controller read sequentially ahead of requested data and to store the
additional data in cache memory, thereby anticipating that the data will be needed soon. This process speeds
up reads for sequential data, but there is little improvement when the computer accesses random data.
— Ahead – Disables the read ahead capability.
 Write Policy – Select one of the following options to specify the write policy for this virtual drive:
— Write Back – In this mode, the controller sends a data transfer completion signal to the host when the
controller cache receives all of the data in a transaction. If you select the Write Back policy and the battery is
absent, the firmware disables the Write Back policy and defaults to the Write Through policy.
— Write Through – In this mode, the controller sends a data transfer completion signal to the host when the
drive subsystem receives all the data in a transaction.
— Always Write Back – In this mode, the controller sends a data transfer completion signal to the host when the
controller cache receives all the data in a transaction. If you select the Always Write Back policy and the battery
is absent, the firmware is forced to use the Write Back policy.
 I/O Policy – The I/O policy applies to reads on a specific virtual drive. It does not affect the read ahead cache.
— Cached – In this mode, all reads are buffered in cache memory. Cached I/O provides faster processing.
— Direct – In this mode, reads are not buffered in cache memory. Data is transferred to the cache and the host
concurrently. If the same data block is read again, it comes from cache memory. Direct I/O makes sure that
the cache and the host contain the same data.
 Disk cache policy – Select a cache setting for this virtual drive:
— Enable – Enable the drive cache.
— Disable – Disable the drive cache.
— Unchanged – Updating the drive cache policy to Unchanged may enable /disable the drive cache based on
the WCE (Write Cache Policy) bit of the save mode page of the drive.
 Emulation – Lets you to set the emulation type on a virtual drive to default or none. The force option forces the
emulation to be set on a controller even when MFC settings do not support it. The possible options are Default,
Disabled, or Forced.
 Initialize – Select to initialize the virtual drive. Initialization prepares the storage medium for use. Fast initialization
will be performed on the virtual drive.
 Configure Hot Spare – Select to configure physical drives as hot spares for the newly created virtual drive.
This option is enabled only if there are additional drives and if they are eligible to be configured as hot spares. This
option is not applicable for RAID 0. If you select this option after the Virtual drive is created, a dialog appears. The
dialog asks you to choose the physical drives that you want to configure as hot spares.