On Fri, 2010-06-11 at 16:57 -0400, Phillip Susi wrote: > I am seeing access to > 2tb on a dm target silently wrap around to 0. > Simple recreation steps: > > lvcreate --type zero -L 3TB -n empty vg0 > lvcreate -s vg0/empty -L 10G -n thin > mke2fs -t ext4 -E lazy_itable_init /dev/vg0/thin > e2fsck -f /dev/vg0/thin > > The fsck will find block bitmap differences on a cleanly formatted fs > that seem to be caused by wraparound. Accessing block 536870912 with dd > seems to return the superblock instead of the block allocation bitmap > that should be located there. > > This is using kernel 2.6.31-21-generic-pae i686 build from Ubuntu 9.10. > > Is this a known issue and/or can anyone reproduce it? So best guess is that CONFIG_LBDAF isn't set. This would make all sector_t counts wrap at 2TB (32 bits worth of 512 bytes). It would be rather a daft thing for a distribution not to have set, though ... James -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
