Dell H310, H710P 2. Virtual Disk Parameters and Descriptions continued, Write Policy, Read Policy

Table 5-2. Virtual Disk Parameters and Descriptions (continued)

Parameter	Description
Write Policy	Write Policy specifies the controller write policy. You can set the write
	policy to Write-Back or Write-Through.
	In Write-Backcaching, the controller sends a data transfer
	completion signal to the host when the controller cache has received
	all the data in a transaction.
	NOTE: If a Battery Backup Unit (BBU) is present, the default cache
	setting is Write-Back. If no BBU is present, the default cache policy
	default setting is Write-Through.
	NOTE: If Write-Backis enabled and the system is quickly turned off and
	then on, the controller may pause as the system flushes cache memory.
	Controllers that contain a battery backup default to Write-Backcaching.
	In Write-Throughcaching, the controller sends a data transfer
	completion signal to the host when the disk subsystem has received
	all the data in a transaction.
Read Policy	Read-Aheadenables the read ahead feature for the virtual disk.
	You can set the parameter to Read-Ahead, No-Read-Ahead,
	or Adaptive. The default is Adaptive-Read-Ahead.
	Read-Aheadspecifies that the controller uses Read-Aheadfor the
	current virtual disk. Read-Aheadcapability allows the controller to
	read sequentially ahead of requested data and store the additional
	data in cache memory, anticipating that the data is required soon.
	No-Read-Aheadspecifies that the controller does not use read ahead
	for the current virtual disk.
	Adaptive specifies that the controller begins using Read-Aheadif the
	two most recent disk accesses occurred in sequential sectors.
	If all read requests are random, the algorithm reverts to
	No-Read-Ahead; however, all requests are still evaluated for
	possible sequential operation.

Management Applications for PERC Cards

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