Hello people, I am trying to create a modified KNOPPIX using devmapper RW snapshots instead of its unionfs solution. The problem is: I get corrupted data and cannot see where it comes from. The relevant part of setup code is attached below. The resulting snapshot volume looks ok at the first glance (dmsetup status) and can be mounted (ext2), the directory tree is displayed but it returns corruped data on most files. I cannot see the problem, a simulation with the same setup method in another environment (kernel 2.6.13) did work as expected. Also Ubuntu uses that method for their Live CD and there it works as well. I looked for a good and up-to-date documentation of the snapshot target but could not find anything. I hope someone can give me a clue, I cannot see how I could solve the problem now. # state: KNOPDEV is /dev/cloop, readonly block device and mounted on # /KNOPPIX, DMSETUP is a static. linked version from devmapper-1.01.04, # kernel is .2.6.12 (.4 or so) COW_NAME=COW CHUNK_SIZE=8 SNAPSHOT_NAME=knop_rw VOL_SIZE=$(blockdev --getsize $KNOPDEV) # create space for the cow data and assign it to a free loop device COWDEV echo | dd bs=1 of=/ramdisk/$COW_NAME seek=`expr 512 \* $VOL_SIZE` count=1 2>/dev/null for x in /dev/loop* ; do if losetup $x >/dev/null 2>&1 ; then continue ; else COWDEV=$x ; break ; fi ; done losetup $COWDEV /ramdisk/$COW_NAME umount /KNOPPIX # critical part, no /KNOPPIX/* system tools for now $DMSETUP mknodes echo "0 $VOL_SIZE linear /dev/cloop 0" | $DMSETUP create knop_ro # this was expected to be a workaround, mapping the loop device to a # devmapper volume. It did also fail when using pure $COWDEV echo "0 $VOL_SIZE linear $COWDEV 0" | $DMSETUP create cow echo "0 $VOL_SIZE snapshot /dev/mapper/knop_ro /dev/mapper/cow p $CHUNK_SIZE" | $DMSETUP create $SNAPSHOT_NAME $DMSETUP mknodes $SNAPSHOT_NAME #remount /static/mount /dev/mapper/$SNAPSHOT_NAME /KNOPPIX # we are back, rewritable bash # And this bash command running on /KNOPPIX already fails with obscure # errors. Thanks, Eduard. -- <Getty> LOL die Telefonnummer vom Arbeitsamt Mönchengladbach ist echt 404-0? <Getty> Soll das nen schlechter Scherz sein? -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
