~/Images $ qemu-img create -f qcow2 test.img 1G
Formatting 'test.img', fmt=qcow2 size=1073741824 encryption=off cluster_size=65536 
~/Images $ qemu-io
qemu-io> open test.img
qemu-io> length
1 GiB
qemu-io> info
format name: qcow2
cluster size: 64 KiB
vm state offset: 1 GiB
qemu-io> read -v 512 1k
00000200:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00000210:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
000005f0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
... ...
read 1024/1024 bytes at offset 512
1 KiB, 1 ops; 0.0000 sec (65.104 MiB/sec and 66666.6667 ops/sec)
qemu-io> close

~/Image # qemu-io -c "read -v 512 1k" mint-arm.img

~/Image # qemu-io -c "readv -v 512 1k 1k 1k" mint-arm.img