LSI Logic Megaraid

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On Linux all management tools communicate with the controller through a character device called "megadev$n" with the major number 254 and the minor $n.[1]


 crw-r--r--    1 root     root     254,   0 May 29 13:43 /dev/megadev0


Unbranded controllers offer either a GUI (which requires a PS/2 mouse attached to the computer) or a "terminal interface". Branded ones (at least Intel) only offer the GUI variant.


ncurses-based management tool. Looks exactly like the terminal-style management interface.



CLI-management tool. Necessary since many tasks are only complicated or not possible with megamgr.

Here's a short command reference for often needed tasks since the documentation is less than optimal:

  • megarc ?

Shows the megarc help, listing all of its 66 flags

  • megarc -dispCfg -a0

Shows the current config.

  • megarc -LogPhysInfo -a0

Shows all logical volumes and physical drives

  • megarc -delLD -a0 -Ln

Deletes the given logical volume. THIS IS FINAL! BE DEARLY SURE OF WHAT YOU'RE DOING!

  • megarc -addCfg -a0 -R5[0:0,0:1,1:0]

Creates a RAID5 consisting of the given physical drives (BUS:TARGET).

  • megarc -spanaddcfg -a0 -R10 -array0[0:1,1:1] -array1[0:2,1:2] -array2[0:3,1:3] -array3[0:4,1:4]

Creates a RAID 10 consisting of the given RAID1-members. The arrays can only consist of two drives.

  • megarc -saveCfg -f/tmp/file -a0

Saves the current configuration to the given file. Could be restored with -restorCfg, although this is still UNTESTED.

  1. At least in 2.4 and 2.6. Be sure to check /proc/devices for the actual numbers if you should run into problems

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