Virtual disk cache policies
NOTE:
Configuring virtual disk cache policies on NVMe PCIe SSD is not
supported.
The PERC S140 uses part of system memory for cache. It supports the following cache options:
•
Read Ahead/Write Back
•
No Read Ahead/Write Back
•
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
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.
16
Virtual Disks
