ext-2 and ext-3 lock a per-inode mutex for the duration of a write. This means that ext-2 and ext-3 do not allow concurrent writes to a file and that can prevent you from getting the write throughput you expect when you stripe a file over several disks with RAID. XFS does not do this which is one of the reasons many people prefer XFS for InnoDB.
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XFS, ext and per-inode mutexes
I didn’t know this. So if you’re using InnoDB with O_DIRECT on a server with RAID, you’d really be well off using XFS. I’m guessing if you don’t use O_DIRECT, your writes just end up getting cached in the buffer cache, and the write throughout issue won’t be pronounced. Domas made a benchmark to test this behavior.
