What is maximum writing speed of the Azure Virtual HD on Windows 10 as the system drive "C:"?

The best way to find out the maximum writing speed of your Azure Virtual HD as the system drive "C:" is to run writing tests with a single large block of different block sizes:

sqlio -LS -kR -i1 -f1 -t1 -s30 -p0 ...

If we run SQLIO with above options and different block sizes, we should be able to find the maximum writing speed:

             Throughput   Throughput   Latency
Block Size      MBs/sec      IOs/sec        ms
----------   ----------   ----------   -------
      -b16         3.73       239.03         3
      -b64        12.85       205.66         4
     -b256        36.56       146.26         6
    -b1024        63.85        63.85        15
    -b4096        75.33        18.83        52
   -b16384        97.49         6.03       169
   -b65536        96.38         1.50       663
  -b262144        96.08         0.37      2446

As you can see, the maximum writing speed, 97.49 MBs/sec is reached with a block size of "-b16384", or 16 MB.

Comparing to the maximum reading speed of 3904.09 MBs/sec, the maximum writing speed of 97.49 MBs/sec is about 40 times slower. So Azure Virtual HD is configured for high speed reading, but not for writing.

⇒ Azure Virtual HD on Windows 10 as D: - 64-KB Benchmark

⇐ Azure Virtual HD on Windows 10 as C: - Maximum Reading Speed

⇑ I/O Tests on Azure Virtual HD and Storage

⇑⇑ SQLIO Disk I/O Benchmark Test Tutorials