Minread Help File
(8/19/96)

Minread is a Response Probe test to help you determine how disk performance  
varies when reading one sector of the disk at a time, the smallest possible 
read unbuffered by the file system cache. 512 bytes is the most common sector size, so this test is set up to do sequential, unbuffered 512-byte reads from a 20Mb file.  Use Performance monitor to analyze the results.


 -- For details on Response Probe, see:
    Windows NT Workstation Resource Guide
    Part 3, Optimizing Windows NT Workstation
    Chapter 11, Performance Monitoring Tools
    Response Probe

 -- For more information about using Performance Monitor to test disk 
    performance, see:
    Windows NT Workstation Resource Guide
    Part 3, Optimizing Windows NT Workstation
    Chapter 14, Detecting Disk Bottlenecks

If your disk has a different sector size, you can change this test to match 
it.  To determine the sector size of your disks:

1.  From the Adminstrative Tools group, select Windows NT Diagnostics. 
2.  Click the Drives tab.
3.  Double-click the letter representing the disk drive.  The disk properties 
    page appears.  Click the General tab. The sector size is displayed under 
    the heavy line.
4.  If the sector size is different, edit Minread.sct.  Change the RECORDSIZE 
    parameter to the size of your sector.


To run Minread, 

1.  Install the required files from the Resource Kit CD onto the drive you
    want to test. (All files except for Workfile.dat are installed as
    part of the Performance Tools group by the CD Setup utility.)

    The following files are required:

    Probe.exe
    Probeprc.exe
    Minread.scr
    Minread.scp
    Minread.sct
    Workfile.dat

    By default, Probe.exe and Probeprc.exe are installed in the 
    \Perftool\Probe subdirectory. The Minread.sc* files are installed
    in the Perftool\Probe\Examples subdirectory. 

    Workfile.dat is not installed by the Setup utility, but you can copy it
    manually from the CD. Workfile.dat is a 20MB file filled with zeros 
    that Response Probe uses to simulate a workload file. You can use
    Workfile.dat or you can create a zero-filled file of any size by using
    the Createfile (Creatfil.exe) utility in the \Probe subdirectory. At 
    the command prompt, type: creatfil <filename> [<filesize>]. The filesize
    is optional; the default is 1024K bytes.)

2.  If you haven't done so already, you need to enable the Performance 
    Monitor disk counters. Once you do, they remain enabled until you 
    disable them.  

    Run the Diskperf utility that comes with Windows NT to enable the
    Performance Monitor disk counters.  At the command prompt, type:

    diskperf -y 
    (for standard disk configurations)
   
    -or-

    diskperf -ye 
    (for stripe sets, mirror sets, or stripe sets with parity)

    
    then, restart the computer. 
    
    If you want to disable the disk counters when your testing is complete,
    at the command prompt, type diskperf -n, then restart the computer.
                               

3.  Start a Performance Monitor log. If possible, write the log to a 
    different physical drive. Log the Logical Disk object at a one 
    second update interval.


4.  At the command prompt of the drive you want to test, change to the 
    subdirectory where the .sc* files are stored and type:

          <path>Probe minread.scr 900

    Note: Minread must be run from the subdirectory where the .sc* files
          are stored. By default, the .sc* files are stored in the 
          \Probe\Examples subdirectory. To run Minread, copy all of 
          the required files to a single subdirectory or run from the
          directory where the .sc* files are stored.
                                                       
5.  When the command prompt returns, stop the Performance Monitor log.


6.  Analyze the data from the test using the Response Probe output file, 
    Minread.out and your Performance Monitor log. Use the following 
    Performance Monitor counters:

    Logical disk: Avg. Disk Bytes/Read
    Logical disk: Avg. Disk sec/Read
    Logical disk: Disk Read Bytes/sec
    Logical disk: Disk Reads/sec






    





