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How to Verify/Repair a RAID Volume
Mac OS X Lion introduced an ugly little bug: Disk Utility will not verify or repair a RAID volume (mirror or stripe). Mac OS X Lion originally could not even display RAID properly (since fixed). The superficial issue is fixed, the important one is not fixed (as of Mac OS X 10.7.4).
Here’s the workaround (works on any volume). My RAID-0 stripe volume Master is verified by the command-line version of Disk Utility ('diskutil').
diglloyd:MPG lloyd$ diskutil verifyVolume Master
Started file system verification on disk7 Master
Checking file system
Performing live verification
Checking Journaled HFS Plus volume
Checking extents overflow file
Checking catalog file
Checking multi-linked files
Checking catalog hierarchy
Checking extended attributes file
Checking volume bitmap
Checking volume information
The volume Master appears to be OK
Finished file system verification on disk7 Master

Grem M writes:
I have a software RAID (striped) created by Disk Utility. Running 10.7.4,
Yes, the Repair/Verify buttons don't work in Disk Utility.
However, I use Onyx and it works for both verify and repair.
DIGLLOYD: I’m also told that Drive Genius works as well.