STB Suite

DMM – Skip Y by Time


The new Skip Y access methods in DMM vs 9.3 allow you to write a data pattern, covering as much of the full LBA range of a drive, while limiting the test to the user-specified time.

To show how this works we will compare this new method with the old method of simply specifying a Write test to run for one hour.

This example will use a 4TB drive which has an average transfer rate of 150 MB/s.

At that speed we can write a maximum of 540GB (150 MB/s X 3600 seconds).

With a Sequential Write test this will write the first 1/8th of the drive

4 TB total LBAs

540 GB at beginning of LBA range


With the new Skip Y access method the same 540 GB of blocks will be written, but they will be spread evenly across the entire LBA range of the drive

4 TB total LBAs

540 GB spread over entire LBA range   


In both cases the Write test runs for 1 hour.

But in the case of the Skip Y test the Writes are spread over the entire range of the drive




How to Define the Skip Y Write Test by time

  1. In DMMs Test Setup tab click on the Test Type Extern. Step
  2. Fill in the Command Line Parameters box with the time to run (hours=n), a comma, and the data pattern to use. In this case we enter hours=1,pattern=allzeros
  3. Fill in the External Program Executable box with either writesamesata (for SATA drives) or writesamescsi (for SAS/SCSI/FC drives)
    Note: for SATA drives specify writesamesata, for SAS drives specify writesamescsi
  4. Click the Add This Test to Test Sequence button. The Test Sequence box will show the test added like this
    Clicking the View Test Sequence Details button will show the test parameters you’ve specified


Data Patterns Available

You may specify any of the following data patterns to be used in the test

  1. pattern=allzeros
  2. pattern=allones
  3. pattern=altzeroandone
  4. pattern=altoneandzero
  5. pattern=incrementing
  6. pattern=decrementing
  7. pattern=random
  8. pattern=walkingzeros
  9. pattern=walkingones
  10. pattern=alt1and0thenalt0and1
  11. pattern=alt0and1thenalt1and0


Log File Output

The DMM .log file will show the test parameters and the results of the test


>> SCSI Toolbox32, Version 9. 3. 0 (build) 160819, running on \\WIN-E7QQNS8J6S<<
>> Default Driver: 10, Operating System: Windows 8 / Server 2012<<
>> Number of Drives Under Test: 1 <<
>> Available Memory (in GB): 1.03 <<
>> SN: 0x00100d31 (3377) <<

Test Date:  10/03/2016  14:43:40
Test Pass:  1

Device:  4:3:0   Vendor: ATA, Product: ST4000NM0053-1C1   Serial:             Z1Z08LYE, Version: SS03

Capacity: 4,000.79 GB, BlockSize: 512 (0x200)


10/03/2016  14:43:41  TEST 1 of 1:

External Program Test, executable = writesamesata
Stop-on-Error Type: Stop Current Test

String Data from the External Program follows:


    WriteSameSATA Wrote: 858,783,744 Blocks,
    Skipped: 6,955,253,424 Blocks,
    Percent Written: 10.99%,
    Cap: 7,814,037,168 Blocks,
    Transfer Rate: 102.88 MB/sec,
    Cmd Line Parameters: pattern=walkingones,hours=1.13



10/03/2016  15:51:37  Worker ID: 1
10/03/2016  15:51:37  Test Completed Successfully

10/03/2016  15:51:37                                                 PASSED