Managing RAID on Linux - Derek Vadala [90]
Depending on how many disks you have selected for inclusion in your new RAID-1, EzAssist will allow you to change the RAID level on the Logical Drive Definition screen. Changing the RAID level to anything other than RAID-1 will be catastrophic and result in total data loss from the previous system.
Use the TAB key to activate the menu on the right side of the screen. Then select Add Disk. The array now appears in the dialog window at the bottom of the screen. Choose Apply to commit the array to the controller's memory.
After the new configuration is written to the controller, return to the main menu and select Perform Administration On → Physical Device.
A list of disks is presented. Select the second disk in the array—that is, the disk that has no preexisting data.
Choose Advanced Options from the menu that appears and then select Make Drive Offline.
A two-step confirmation appears. Answer yes to both questions. Now the drive is marked offline.
Finally, return to the main menu and choose Perform Administration On → Logical Drive.
Select the array that contains the member disk that you just marked offline; the disk will appear highlighted and in critical condition.
Choose Advanced Options and Rebuild Redundancy Data from the menu that pops up.
A confirmation appears. Answer affirmatively. After a short pause, you are returned to the array status menu, and the array is now marked as rebuilding.
* * *
* * *
You can monitor the progress of the rebuild process by selecting Advanced Options and then Background Tasks from EzAssist's main menu. After the rebuild process has completed, you can reboot your system. System partitions that were on the original JBOD logical drive are now mirrored.
In general, you can delete any JBOD disk and create a new RAID-1 with the former JBOD drive as its first component. The process also works in the other direction. Delete any mirror and then create a JBOD logical drive that contains a former RAID-1 member to return to single disk operation.
Managing Arrays
You can manage arrays using the DAC960/DAC1100 driver's /proc entry, but its functionality is limited. To manage all aspects of your Mylex controller without bringing down the system, you will also need to use the Mylex Global Array Manager.
/proc/rd
The DAC960/DAC1100 driver uses the /proc/rd directory to report information about the status of Mylex controllers and to provide a user interface for performing some online management functions.
/proc/rd/status provides a simple interface for determining the status of all Mylex controllers connected to the system. When all controllers are operating normally, the status file returns OK:
$ cat /proc/rd/status
OK
If an array is degraded or failed, or a physical disk has failed, /proc/rd/status reports an alert:
$ cat /proc/rd/status
ALERT
Detailed status information is provided in controller-specific directories named /proc/rd/cN, where N is the controller number. Each controller subdirectory contains three files: current_status, initial_status, and user_command. Examine current_status using cat or a file pager to view the controller state of a controller and its arrays. A lot of information is displayed. The initial output is similar to what is provided by the controller's startup banner and is found in the controller configuration menu under EzAssist:
***** DAC960 RAID Driver Version 2.4.11 of 11 October 2001 *****
Copyright 1998-2001 by Leonard N. Zubkoff Configuring Mylex AcceleRAID 352 PCI RAID Controller Firmware Version: 7.00-03, Channels: 2, Memory Size: 64MB PCI Bus: 2, Device: 13, Function: 0, I/O Address: Unassigned PCI Address: 0xF0000000 mapped at 0xD083F000, IRQ Channel: 9 Controller Queue Depth: 512, Maximum Blocks per Command: 2048 Driver Queue Depth: 511, Scatter/Gather Limit: 128 of 257 Segments Next, a list of physical disks is displayed, including