Data movement statistics

The data movement chart displays the migration actions that are triggered by Easy Tier®.

The data movement chart displays the data for the previous 24-hour period, in one-hour increments. You can change the span of time display, and the increments that you would prefer, such as hourly.

To view Easy Tier data and reports in the management GUI, select one of the following paths:
  • From the management GUI, select Monitoring > Easy Tier Reports
  • From the management GUI, select Pools > View Easy Tier Reports

Access the data movement statistics chart by selecting the Data Movement tab.

The first time that you open the Easy Tier reports page, the Data Movement chart is automatically displayed. After you modify this chart, or view a different chart, your last action is retained until a new set of data is acquired through the Easy Tier Statistics tool. (The tool processes the Easy Tier data and generates the HTML reports and CSV files).

The following list describes the type of data that is displayed in the chart:

Extent capacity
The Y-axis displays the number of moved capacity extents. Promoted (rebalanced) extents display above the line, and demoted (swapped) extents are displayed below the line.
Selected viewport time
Displays the time and date that is rendered in the viewport selection.
Viewport X-axis time selection
Displays the time selection in hours. Values that can be chosen are in hours, and the options are 24, 12, 6, 4, 3, 2, or 1 hour.
Restriction: Displaying large amounts of data, such as a 24-hour period in 5-minute increments, is limited to the display area. There is not enough display space to see all 288 data points in the viewport. Use the horizontal scroll bar to view all the data. You can also use the viewpoint shifter to move to the next set of data that is not being displayed in the current viewpoint.
X-axis increment selection
Displays the time that is selected in increments. You can modify the increments to choose the time that is displayed in the viewport. Values are 1 hour, 30 minutes, 15 minutes, 10 minutes, or 5 minutes, depending on the increments available for that section.
Data movement key
Displays all the data movement actions that take place. The types of actions are:
Promote
When active data is moved from a lower tier of storage to a higher tier to improve the overall system performance.
Warm Promote
When an MDisk becomes overloaded, active data is moved from a lower tier to a higher tier to reduce the workload on the MDisk.
Balancing Move
When data is moved within the same tier from an array with a higher workload, to one with a lower workload to balance the workload within the tier.
Balancing Swap
When data is moved within the same tier from an array with higher workload, to one with a lower workload to balance the workload within the tier.
Promote Swap
When active data is moved from a lower tier of storage to a higher tier, other less-active data must first be moved to make space.
Warm Demote
When an MDisk becomes overloaded, active data is moved from a higher tier to a lower tier to reduce the workload on the MDisk.
Cold Demote
When inactive, or less-active data is moved from a higher tier of storage to a lower tier to free up space on the higher tier.
Movement details
Displays a textual and visual description of the different data movement actions that are listed in the key.
The detailed format is described in the following table:
Table 1. Data move statistic descriptions
Data Data format Definition Comments
index Integer Row number  
dss String Cluster ID IBM.2145-169933
volume_id Integer Volume ID (vdisk ID) Example: 0
copy_id Integer cdisk ID Example: 0
extent Integer The ID of the extent in this volume  
time ISO 8601 format The time stamp when the movement happened 2016-10-26T21:37:05+05:00
type Integer Small write IOPS targeted against that data Possible Value: 1~10
typedescription String Small read IOPS targeted against that data
Possible values:

  • PROMOTE(type=1) /* Move an extent to a more capable tier */

  • SWAP(type=2) /* Move an extent to a less capable tier which frees space on a more capable tier. Also move an extent to the more capable tier. */
  • DEMOTE(type=3) /* Move an extent to a less capable tier */
  • MOVE(type=4) /* Move an extent to another mdisk in the same tier */
  • RB_SWAP(type=5) /* Swap extents between mdisks in the same tier */
  • WARM_DEMOTE(type=6) /* Move an extent to a more capable mdisk in another tier */
  • WARM_PROMOTE(type=10) /*
source Integer Small IO Bandwidth targeted against those data mdisk number
target Integer Large write IOPS targeted against those data mdisk number