Dell H710P, H310, H810 manual Parameter Description, Summary Of RAID Levels

For more information, see the topic Managing Dedicated Hot Spares.

3.Initialize the virtual disks.

NOTE: When you use one physical disk group to create multiple virtual disks, all the virtual disks must be configured with the same RAID level.

When you define the virtual disks, you can set the following virtual disk parameters:

–RAID level

–Stripe element size

–Read policy

–Write policy

–Type of initialization

–Hot spare configuration

NOTE: The default hard drive cache policy for a virtual disk composed with SAS hard drives is disabled and with SATA hard drives is enabled. The Virtual Disk parameter cannot be changed in the BIOS Configuration Utility (<Ctrl> <R>). Use Dell OpenManage Storage Management for the hard drive cache setting operation.

The following table shows the parameters that you can configure when defining virtual disks.

Parameter	Description
RAID Level	RAID Level specifies whether the virtual disk is RAID 0, 1, 5, 6, 10, 50, or 60. The number of
	disks, disk capacity, the requirements for fault tolerance, performance, and capacity
	should be considered when selecting the RAID level. For more information, see the topic
	Summary Of RAID Levels.

Stripe Element Size

Write Policy

Read Policy

Stripe Element Size specifies the size of the segments written to each physical disk in a RAID 0, 1, 5, 6, 10, 50, and 60 virtual disk. You can set the stripe element size to 64 KB 128 KB, 256 KB, 512 KB, or 1024 KB. The default and recommended stripe element size is 64 KB.

A larger stripe element size provides better read performance if your system mostly does sequential reads.

Write Policy specifies the controller write policy. You can set the write policy to Write- Back or Write-Through.

In Write-Back caching, 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-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.

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