[Following up on this thread: http://thread.gmane.org/gmane.linux.kernel.device-mapper.devel/14999] Alasdair G Kergon wrote: > Try > blkdev --flushbufs > after any cmd that writes to a dev to see if that makes any difference. Thanks for the work-around. Using "blockdev --flushbufs $dev" does indeed make parted behave the same with dm-backed storage as with other devices. Adjusting my small example, cd /tmp; truncate -s 10m g && loop=$(losetup --show -f g) echo 0 100 linear $loop 0 | dmsetup create zub dev=/dev/mapper/zub parted -s $dev \ mklabel gpt \ mkpart efi 34s 34s \ mkpart root 35s 35s \ mkpart roo2 36s 36s \ u s p blockdev --flushbufs $dev # FIXME: required with device-mapper-1.02.65-5 # write random bits to p1 dd of=${dev}p1 if=/dev/urandom count=1 dd if=${dev}p1 of=p1-copy.pre count=1 parted -s $dev mkpart p4 37s 37s blockdev --flushbufs $dev # FIXME: required with device-mapper-1.02.65-5 dd if=${dev}p1 of=p1-copy.post count=1 cmp -l p1-copy.pre p1-copy.post With that, the "cmp" show no differences. Does this sound like a problem in device-mapper land, or in how parted interacts with DM? -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
