- 11 -
ServeRAID M5210 SAS/SATA Controller for IBM System x User’s Guide
July 2014
Chapter 1: Overview
Benefits of the ServeRAID M5210 SAS/SATA Controller
A fundamental component of the T10 data protection model is the addition of 8 bytes of extra protection information
transferred with each block of user data in the storage system, as shown in the following figure. Although not
specifically named in the T10 standards, this collection of 8 bytes is commonly referred to as the DIF. The DIF contains
three distinct values: a 2-byte logical block guard, a 2-byte logical block application tag, and a 4-byte logical block
reference tag. The T10 specification defines four types of usage models of data protection: Type 0, Type 1, Type 2, and
Type 3 (refer to the most current revision of INCITS T10/1799-D for further information)
Figure 3 T10 Data Integrity Field for MegaRAID Protection Information
1.5.9
Drive Roaming
Drive roaming occurs when the physical disks are changed to different ports on the same controller. When the drives
are placed on different channels, the controller detects the RAID configuration from the configuration data on the
drives.
Configuration data is saved in both the NVRAM on the RAID controller and on the drives attached to the controller.
This action maintains the integrity of the data on each drive, even if the drives have changed their target ID.
Follow these steps to use drive roaming:
1.
Turn off the power to the server and all physical disks, enclosures, and system components. Disconnect the power
cords from the system.
2.
Remove the server cover by following the instructions in the host system technical documentation.
3.
Move the drives to different positions on the backplane to change the targets.
4.
Determine the SAS target requirements.
5.
Perform a safety check.
6.
Make sure that the drives are inserted correctly.
7.
Reinstall the server cover.
8.
Reconnect the power cords to the system.
9.
Turn on the power to the system.
10. The controller then detects the RAID configuration from the configuration data on the drives.
NOTE
In a clustering environment, drive roaming is supported within the same channel only.
NOTE
If you move a drive that is being rebuilt, the rebuild operation restarts; it does not resume from where
the rebuild operation stopped.
