Additions to the SYSDISKSTAT

SYSDISKSTAT returns the information about disk and solid-state drives, SSD. It comes in two forms:

• SYSDISKSTAT View
• SYSDISKSTAT Table function

I am not going to say much more about using these two as I gave a lot of detail when they were first introduced.

In the latest release IBM i 7.6 and 7.5 TR6 two new columns have been added to both of the SYSDISKSTAT:

1. BLOCK_SIZE:  Size of each page on the disk unit.
2. UNMAP_CAPABLE:  Can the disk unit perform the unmap function to return the unused pages to the unallocated area? Allowed values are 'NO' and 'YES'.

I am a developer, not an system admininstrator, therefore, I have to admit I do not know what the ramifications of the details in this columns are. But, I know many system admins who use SYSDISKSTAT as it returns lot of interesting information about the storage, in a simple manner.

If I was to use the SYSDISKSTAT View to show these two new columns I would a statement like this:

01 SELECT RESOURCE_NAME,RESOURCE_STATUS, 02 BLOCK_SIZE, 03 UNMAP_CAPABLE 04 FROM QSYS2.SYSDISKSTAT 05 ORDER BY RESOURCE_NAME 06 LIMIT 5

Line 2: The first new column.

Line 3: The second.

Line 4: Get the data from the View.

Line 5: Order the results by the resource name.

Line 6: And return the first five results. I only want the first five results as this is just an example.

The results are:

RESOURCE BLOCK UNMAP_ _NAME _STATUS _SIZE CAPABLE -------- -------- ----- ------- DMP001 PASSIVE 512 YES DMP002 PASSIVE 512 YES DMP003 ACTIVE 512 YES DMP004 ACTIVE 512 YES DMP005 PASSIVE 512 YES

All of these resources block size is 512 bytes, and they can unmap the unused pages.

I can do the same thing with the Table function:

01 SELECT RESOURCE_NAME,RESOURCE_STATUS, 02 BLOCK_SIZE, 03 UNMAP_CAPABLE 04 FROM TABLE(QSYS2.SYSDISKSTAT(RESET_STATISTICS => 'YES')) 05 ORDER BY RESOURCE_NAME 06 LIMIT 5 07 OFFSET 5

Lines 1 – 3: The columns I want in the results are the same as the previous statement.

Line 4: I am using the SYSDISKSTAT Table function, and asking it to reset the statistics. I know that this does not have an effect on the results of my statement, I just wanted the opportunity to show it.

Line 5: As before I want the results to be ordered by resource name.

Line 6: Return five results.

Line 7: I am using the offset clause as I do not want the first five results; I want five rows starting from the six row of the results.

The results are:

RESOURCE RESOURCE BLOCK UNMAP_ _NAME _STATUS _SIZE CAPABLE -------- -------- ----- ------- DMP006 PASSIVE 512 YES DMP007 ACTIVE 512 YES DMP008 PASSIVE 512 YES DMP009 ACTIVE 512 YES DMP010 ACTIVE 512 YES

Which are pretty much the same as the first set of results.

I am sure my system administrator friends will find these columns interesting; I am pretty certain I will never use them.

 

You can learn more about this from the IBM website:

• SYSDISKSTAT View
• SYSDISKSTAT Table function

 

This article was written for IBM i 7.6 and 7.5 TR6.