Am 21.05.25 um 17:32 schrieb Eric Blake: > On Wed, May 21, 2025 at 11:54:03AM +0200, Fiona Ebner wrote: >> I also tried it on my host, where the filesystem is ZFS using >> compression, and there, 'du' will already report a lower value after >> creating the image, because of compression. And even without compression >> it seems that preallocation=full on ZFS is somehow async :/ >> >>> [I] febner@enia ~/qemu/build/tests/qemu-iotests (master)> qemu-img create >>> my.raw 20M -f raw -o preallocation=full >>> Formatting 'my.raw', fmt=raw size=20971520 preallocation=full >>> [I] febner@enia ~/qemu/build/tests/qemu-iotests (master)> du --block-size=1 >>> my.raw >>> 512 my.raw >>> [I] febner@enia ~/qemu/build/tests/qemu-iotests (master)> du --block-size=1 >>> my.raw >>> 20980224 my.raw > > That one may be a bit harder to work around, but I'll give it a shot > while I'm patching the first one.
FWIW, doing a 'sync' before querying with 'du' will avoid the issue for the allocation. But even then, after mirroring, the file will be sparse again. Best Regards, Fiona
