Normal disks also have a default 128kb readahead, not 4 MB, which seems to be quite sufficient. I don't see why you want the dm device layered on top of the physical disks doing MORE readahead, let alone 4 MB worth. If the setting given to lvchange is not respected though, that is a bug.
Normal disks also have a default 128kb readahead, not 4 MB, which seems to be quite sufficient. I don't see why you want the dm device layered on top of the physical disks doing MORE readahead, let alone 4 MB worth. If the setting given to lvchange is not respected though, that is a bug.