mount
docker@default:/data$ dd if=/dev/zero of=test.dat bs=1024 count=100000
100000+0 records in
100000+0 records out
102400000 bytes (97.7MB) copied, 31.461012 seconds, 3.1MB/s
not mount
docker@default:/tmp$ dd if=/dev/zero of=test.dat bs=10240 count=1000000
1000000+0 records in
1000000+0 records out
10240000000 bytes (9.5GB) copied, 22.488968 seconds, 434.2MB/s
mount docker@default:/data$ dd if=/dev/zero of=test.dat bs=1024 count=100000
100000+0 records in 100000+0 records out 102400000 bytes (97.7MB) copied, 31.461012 seconds, 3.1MB/s
not mount docker@default:/tmp$ dd if=/dev/zero of=test.dat bs=10240 count=1000000
1000000+0 records in 1000000+0 records out 10240000000 bytes (9.5GB) copied, 22.488968 seconds, 434.2MB/s