Firstly there's a real interesting thread about nbdcopy vs qemu-img
convert performance:
https://listman.redhat.com/archives/libguestfs/2021-May/thread.html#00119
I have a question about qemu-img convert -W flag. The documentation
says:
-W Allow out-of-order writes to the destination. This option im‐
proves performance, but is only recommended for preallocated de‐
vices like host devices or other raw block devices.
I don't understand why out of order writes are bad for things like raw
files and qcow2 files, or for non-preallocated block devices.
Wouldn't they always be a win?
Rich.
--
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