Active data distribution

Use this page to view the distribution of data on physical volumes marked full on a IBM® TS7700 Cluster. The distribution can be used to select an appropriate reclaim threshold.

The Active Data Distribution page displays the percent utilization of physical volumes in increments of 10%.

Number of Full Volumes at Utilization Percentages
This table shows the number of physical volumes marked as full in each physical volume pool, according to percentage of volume used. Fields displayed include:
Pool
The physical volume pool number. This number is a hyperlink; click it to display a graphic representation of the number of physical volumes per utilization increment in a given pool.
When you click the pool number hyperlink, the Active Data Distribution sub page opens. This sub page contains the following fields and information:
Pool
To view graphical information for another pool, select the target pool from this drop down menu.
Current Reclaim Threshold
The percentage used to determine when to perform reclamation of free storage on a stacked volume. When the amount of active data on a physical stacked volume drops below this percentage, a reclaim operation is performed on the stacked volume.

Physical volumes hold between the threshold value and 100% of data. Setting the threshold too low results in more physical volumes being needed; setting the threshold too high might affect the ability of the TS7700 Tape Attach to perform host workload because it is using its resources to perform reclamation. Experiment to find a threshold that matches your needs.

The valid range of possible values is 0-95(%) and can be entered in 1% increments; 35% is the default value. If the system is in a heterogeneous tape drive environment, then this threshold is for R/W media.

This percentage is a hyperlink; click it to open the Modify Pool Properties page, where you can modify the percentage used for this threshold.
Number of Volumes with Active Data
The number of physical volumes that contain active data.
Pool n Active Data Distribution
This graph displays the number of volumes that contain active data per volume utilization increment for the selected pool. On this graph, utilization increments (x axis) do not overlap.
Pool n Active Data Distribution (cumulative)
This graph displays the cumulative number of volumes that contain active data per volume utilization increment for the selected pool. On this graph, utilization increments (x axis) overlap, accumulating as they increase.
The Active Data Distribution sub page also displays utilization percentages for the selected pool, excerpted from the Number of Full Volumes at Utilization Percentages table.
Media Type
The type of cartridges contained in the physical volume pool. If more than one media type exists in the pool, each type is displayed, separated by commas. Possible values are:
Any 3592
Any media with a 3592 format.
JA
Enterprise Tape Cartridge (ETC)
JB
Extended Data Enterprise Tape Cartridge (EDETC)
JC
Enterprise Advanced Data Cartridge (EADC)
JD
Advanced Type D Data (ATDD)
JE
Advanced Data E Cartridge (ATED)
JJ
Enterprise Economy Tape Cartridge (EETC)
JK
Enterprise Advanced Economy Tape Cartridge (EAETC)
JL
Advanced Type L Economy (ATLE)
JM
Advanced Type E Economy Cartridge (ATME)
Percentage of Volume Used (0+, 10+, 20+ ...)
Each of the last 10 columns in the table represent a 10% increment of total physical volume space used. For instance, the column heading 20+ represents the 20–29% range of a physical volume used. For each pool, listed is the total number of physical volumes that occur in each range.

For information about the steps you can take to achieve peak network performance, refer to IBM TS7700 Series Best Practices - Understanding, Monitoring and Tuning the TS7700 Performance, WP101465, available from the TechDocs link in the Related information section.