On Mon, Jun 30, 2014 at 10:14:03AM +0100, Joe Thornber wrote: > - There's a constant 4k background load to the metadata device. > > I'll look into this. Sounds like the periodic commit is re writing > the superblock even if there's no change to the mappings. I've added this test to the dm test suite: https://github.com/jthornber/device-mapper-test-suite/blob/master/lib/dmtest/tests/cache/io_use_tests.rb Using my latest development tree I can't see any spurious IO. I also instrumented to see exactly when the superblock is written, again nothing happens while the cache is idle. So I'm puzzled about what you are seeing. - Joe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
