Managing RAID on Linux - Derek Vadala [92]
echo "rebuild 0:4" > /proc/rd/c0/user_command
check-consistency logical drive number
Initiates a consistency check on a logical drive. This process simply verifies that the redundancy information is correct. For example:
echo "check-consistency 0" > /proc/rd/c0/user_command
cancel-rebuild
Cancels all rebuilds that are currently in progress. This command applies to all arrays. For example:
echo "cancel-rebuild" > /proc/rd/c0/user_command
cancel-consistency-check
Cancels all consistency checks that are currently in progress. This applies to all arrays. For example:
echo "cancel-consistency-check" > /proc/rd/c0/user_command
Refer to the file /usr/src/linux/Documentation/README.DAC960 for further information about these commands.
The Global Array Manager (GAM)
The Mylex Global Array Manager (GAM) is used to monitor and manage arrays while the system is running. It's included on the CD-ROM packaged with your controller, but I recommend downloading the most recent update from the Mylex web site. Grab the linux-gam_510.exe file (it's marked GAM for Linux). Since its location might vary, I haven't included it here, but you can find it by navigating to the Driver/Support page. Don't forget that the version number might also change slightly. The file is a self-extracting zip archive, so you'll have to use unzip, not gunzip, to extract the RPM files from it.
$ unzip linux-gam_510.exe
Archive: linux-gam_510.exe
inflating: sam-client-5.00-10.i386.rpm
inflating: gam-client-5.00-13.i386.rpm
inflating: gam-linux-readme_510.txt
inflating: gam-server-5.00-12.i386.rpm
inflating: gam-agent-5.00-12.i386.rpm
The Global Array Manager is comprised of a client (gam-client-5.00-13.i386.rpm) and a server (gam-server-5.00-12.i386.rpm) package. The gam-server package provides the underlying framework for communicating with the controller, and the gam-client package provides the GUI management interface. To install gam-server successfully, you must have either inetd or xinetd installed and running. It's not enough for either program to simply be installed; one of them must be running. That's because the client and server components use TCP/IP to communicate with each other. After installation, a desktop icon is created for KDE and GNOME users. You can also run GAM directly from /opt/gam/bin/gam. The Global Array Manager is very straightforward to use and is well documented. There's built-in HTML help and an installation guide (http://www.mylex.com/pub/support/current_raid/Linux-GAM.pdf). Most of GAM's functions mimic EZAssist.
Adaptec
Adaptec has two RAID controller product lines based on different processors and technologies. This dichotomy stems from Adaptec's history with RAID controllers. In 1999, Adaptec, Inc. acquired Distributed Processing Technology (DPT), a manufacturer of, among other storage products, SCSI RAID controllers. At that time, Linux support for DPT controllers was provided in the form of a GPL kernel patch. Since the acquisition, Adaptec has continued to support Linux in its RAID product line by continuing driver development for controllers based on the original DPT architecture.
After the acquisition, Adaptec began to develop a new product line aimed at OEM controllers. These controllers were featured in server-class systems available from Dell Computer and Hewlett-Packard. Many users will know these controllers as the Poweredge Expandable RAID Controller (PERC). Since the new controllers had a different architecture, a new Linux driver was needed. Eventually, Adaptec released several boxed controllers based on this new architecture. So today, the new driver is used for OEM controllers, as well as some newer boxed products.
* * *
Tip
If you have a Dell system with a branded Adaptec controller, you might want to take a look at Matt Domsch's page on the subject: http://www.domsch.com/linux/. It's the best resource that I've been able to find for Dell's RAID solutions and Linux.
* * *
The controller that you purchase dictates