SOS File Space Utilization

To access the File Space Utilization Screen from the Global Summary screen:

Type S from the SOS Enter command: prompt to view the Screen Selection Menu screen. You may also type J at the Enter command: prompt of any SOS screen.

From the Screen Selection Menu screen, enter U (File Space Utilization Screen). The File Space Utilization Screen will display.

Transient disc space is disc space that is used to temporarily off-load main memory data. Effectively a transient space scheme is an inexpensive way to make main memory look bigger. The most active processes in main memory will have their data in memory, while less active processes’ data will be temporarily sent out to transient disc space.

File Space Utilization Screen Keys

All of the File Space Utilization Screen keys are identical with the keys of the CPU Detail Screen. See "CPU Detail Screen Keys" for details.

File Space Utilization Display Items

Examples of the File Space Utilization screen are provided in "Graphical Format" and "Tabular Format". These screen displays are especially helpful in tracking such things as disc space usage, virtual memory usage (transient space) and disc space fragmentation.

To toggle between a Graphic and Tabular display format press the G key or press the F4 function key (GRAPHIC DISPLAY/TABULAR DISPLAY).

Graphical Format

The graphic display shows key utilization and fragmentation statistics by disc drive and for all disc drives. The left side of the screen shows permanent and transient space utilization. The right side of the screen shows fragmentation by size category (i.e., blocks of less than 100 sector pieces, blocks of less than 1000 sectors, etc.). See Figure 24.1 for a sample display.

Figure 24.1 SOS File Space Utilization screen (graphical format)

File Space Utilization (graphical format)

The File Space Utilization data items are described in the following table.

Table 24.1 SOS File Space Utilization data items

Data Item	Description
Dev	This is the disc drive number.
Permanent/Transient Use %	This is the amount of disc space being utilized by this disc for permanent space (delimited by the letter "P" on the bar graph) and transient space (delimited by the letter "T").
Free space fragmentation %	This is the amount of free space on each disc that is in non-continuous sectors. This mean that if information is saved on this disc and then must be retrieved from it, that information must be gathered from different areas on the disc, thus slowing response time. The bar graphs use the characters "1" through "5" as delimiters to indicate the following: 1 = The percentage of free space which is composed of chunks that are <100 sectors in size. 2 = The percentage of free space which is composed of chunks that are 100 to 999 sectors in size. 3 = The percentage of free space which is composed of chunks that are 1,000 to 9,999 sectors in size. 4 = The percentage of free space which is composed of chunks that are 10,000 to 99,999 sectors in size. 5 = The percentage of free space which is composed of chunks that are 100,000 or more sectors in size. Performance Tip The greater percentage of smaller numbers, the more fragmented is your free space.

Tabular Format

The tabular format shows more detailed information than the graphic format. Figure 24.2 is a sample of the File Space Utilization tabular screen.

Figure 24.2 SOS File Space Utilization screen (tabular format)

File Space Utilization (tabular format)

The following table contains a description of each component of the File Space Utilization tabular screen.

Table 24.2 SOS File Space Utilization data items

Data Item	Description
Dev	The disc drive number.
Used (Trans, Perm)	The amount of disc space being utilized by this disc for transient space and permanent space.
Avail (Trans, Perm)	The amount of free space on this disc for transient use and permanent use. Avail Trans is calculated by substracting Used Trans from Max Trans. Avail Perm is calculated by substracting Used Perm from Max Perm.
Max % (Trans, Perm)	The total percentage of available transient and permanent disc space for which your system is configured. Performance Tip It is important to have enough transient disc space configured on your system to prevent program aborts or delays (if insufficient space exists, applications will not run). An insufficient amount of main memory will cause the memory manager to swap out to disc, which will impact a transaction’s response time.
Contiguous Free Space	The amount of free space on each disc that is in continuous sectors. Largest - The size (in sectors) of the largest contiguous chunk of free space on the given disc drive. <100 - The number of sectors of free space which are composed of chunks that are <100 sectors in size. <1000 - The number of sectors of free space which are composed of chunks that are 100 to 999 sectors in size. <10K - The number of sectors of the free space which are composed of chunks that are 1,000 to 9,999 sectors in size. <100K - The number of sectors of the free space which are composed of chunks that are 10,000 to 99,999 sectors in size. 100K+ - The number of sectors of the free space which are composed of chunks that are 100,000 or more sectors in size.

If you have a lot of free space in <100, you have disc fragmentation. Disc fragmentation, in theory, can contribute to disc I/O impedance. The graphic display of the Disc Space Utilization screen demonstrates Free Space fragmentation beautifully.

Keep in mind that this data is also logged in the SOS/3000 log files. To access this logged data refer to "SOSLOGX". Also note that a list of extractable data items can be found in the Appendices.