Users Guide

● Read Ahead/Write Through

● No Read Ahead/Write Through

Table 6. Read, Write, and Cache Policy for the PERC S140

Category Supported by S140 controller

Cache settings Yes

Read Ahead/Write Back Yes

No Read Ahead/Write Back Yes

Read Ahead/Write Through Yes

No Read Ahead/Write Through Yes

NOTE: The current default for Write-Cache mode enablement is Write Through, No Read Ahead (WT, NRA). To enable

Write Back (WB), a UPS is recommended.

NOTE: For more information about the physical disk write cache policy behavior, see Troubleshooting your system on page

Virtual disk migration

The PERC S140 supports automatic virtual disk migration from one PERC S140 to another.

CAUTION:

The virtual disk is lost if you perform a virtual disk migration during an Online Capacity Expansion

(OCE)/Reconfigure.

NOTE: Back up the virtual disk data before migrating virtual disks.

NOTE: Ensure that all physical disks that are part of the virtual disk are migrated. Virtual disks in optimal and degraded

states are automatically migrated. A virtual disk in an offline state should not be migrated.

NOTE: A bootable virtual disk cannot be migrated between dissimilar system models.

NOTE: When you migrate virtual disks, ensure that you verify that the number of virtual disks does not exceed 10.

Migrating a virtual disk

1. Turn off the system that contains the source controller.

2. Turn off the target system if the system does not support hot swap of physical disks.

3. Move the appropriate physical disks from the source controller to the target controller in the target system.

Physical disks do not have to be inserted into the same slots in the target system.

4. If the target system was turned off, turn on the system.

CAUTION:

The BIOS Configuration Utility pauses, and prompts for action, for the degraded virtual disk(s), if the

"pause if degraded" option is enabled in the BIOS Configuration Utility.

CAUTION: After the migration occurs, ensure that all of the physical disks have been migrated and are present

in the appropriate virtual disks.

Expanding virtual disk capacity

The capacity of a virtual disk can be expanded online by using the Online Capacity Expansion/Reconfigure (OCE/Reconfigure).

OCE/Reconfigure is a process that allows you to add storage capacity to an existing virtual disk. In most cases additional

storage capacity can be added without taking the system offline.

Virtual Disks