How to find out the maximum reading speed of my hard disk?

The best way to find out the maximum reading speed of your hard disk is to run reading tests with a single large block:

• "-LS" - Sets SQLIO to report latency measurements using the system timer.
• "-kR" - Sets SQLIO to perform reading tests.
• "-i1" - Specifies the run size of 1 I/O tests Basically, SQLIO will perform only I/O test in each run.
• "-f1" - Specifies the stripe factor of 1 blocks. This option is useless now, since only 1 block is needed in each run. There will be only 1 stripe.
• "-t1" - Sets SQLIO to use 1 thread only.
• "-s300" - Sets SQLIO to run for 300 seconds, or 5 minutes.

If we run SQLIO with above options and different block sizes, we should be able to find the maximum reading speed. Here are test results on Western Digital - WD5000LPLX-08ZNT 465GB hard disk:

             Throughput   Throughput   Latency
Block Size      MBs/sec      IOs/sec        ms
----------   ----------   ----------   -------
     -b512       327.22       654.44         1
    -b1024       335.12       335.12         2
    -b2048       365.10       182.55         5
    -b4096       326.22        81.55        11
    -b8192       378.95        47.36        20
   -b16384       242.28        15.14        65
   -b32768        96.87         3.02       329
   -b65536        89.00         1.39       718
  -b131072        85.35         0.66      1499
  -b262144        84.42         0.32      3031

As you can see, the maximum reading speed, 378.95 MBs/sec, is reached with a block size of "-b8192", or 8 MB. If the block size is too small, the operating system is not feeding the hard disk with enough requests. If the block size is too big, the operating system is not able to cache it properly.

In other orders, block size of 8 MB makes a perfect match between the operating system and the hard disk.

The test result of "-b4096" seems to be not aligned properly with other tests. It was probably impacted by other system activities

⇒ Western Digital - WD5000LPLX-08ZNT - Maximum Writing Speed

⇐ "sqlio -kW -b1024" - Writing 1-MB Block Test

⇑ Tuning SQLIO for Your Environment

⇑⇑ SQLIO Disk I/O Benchmark Test Tutorials