Table of Contents
Advertisement
Whenever the operating system needs to write to a mirrored volume, both disks are
updated. The disks are maintained at all times with exactly the same information.
When the operating system needs to read from the mirrored volume, the OS reads
from whichever disk is more readily accessible at the moment. This functionality can
result in enhanced performance for read operations.
Caution – Creating RAID volumes using the on-board disk controller destroys all
data on the member disks. The disk controller's volume initialization procedure
reserves a portion of each physical disk for metadata and other internal information
used by the controller. Once the volume initialization is complete, you can configure
the volume and label it using the format(1M) utility. You can then use the volume
in the Solaris OS.
Hardware Raid Operations
On the Sun Netra T5440 server, the SAS controller supports mirroring and striping
using the Solaris OS raidctl utility.
A hardware RAID volume created under the raidctl utility behaves slightly
differently than one created using volume management software. Under a software
volume, each device has its own entry in the virtual device tree, and read-write
operations are performed to both virtual devices. Under hardware RAID volumes,
only one device appears in the device tree. Member disk devices are invisible to the
operating system, and are accessed only by the SAS controller.
Physical Disk Slot Numbers, Physical Device
Names, and Logical Device Names for Non-RAID
Disks
To perform a disk hot-plug procedure, you must know the physical or logical device
name for the drive that you want to install or remove. If your system encounters a
disk error, often you can find messages about failing or failed disks in the system
console. This information is also logged in the /var/adm/messages files.
These error messages typically refer to a failed hard drive by its physical device
name (such as /devices/pci@1f,700000/scsi@2/sd@1,0) or by its logical
device name (such as c0t1d0). In addition, some applications might report a disk
slot number (0 through 3).
54
Sun Netra T5440 Server Administration Guide • April 2010
Advertisement
Table of Contents
