2.1 Tiering Policies

Standard for moving data within the volume by Automated Storage Tiering is defined as "Tiering policy".
The approach in relation to the configuration of Tiering policy is described below.

Evaluation Standard

The "peak value" or "average value" within the evaluation period of IOPS in relation to the target volume, taking into account the access status in order to move data within the volume.

In order to place data with a high IOPS value, even for a short period of time in the evaluation period, onto a rapid disk, "peak value" should be selected. In order to place data with a constantly high IOPS value, "average value" should be selected.
Make a selection according to the state of access to the data of the target volume.

Evaluation Period

This is the period during which the state of access to the data within the target volume is evaluated.
Depending on the system configuration and form of utilization, the following may be selected.

Hour Units (2, 4, 6, 8, or 12 hours)
Day Units (1-31 days)

When a value for day units has been selected, during one day (24 hours), the time of the day to perform the evaluation can be specified. In addition, the time to start evaluation and repositioning of access status data (Automated Storage Tiering Execution Time) can be specified as well.
Upon taking into account the effect on tasks utilizing the target volume, configure an appropriate evaluation period, time frame subject to evaluation, and time to start the relocation.

The optimal value for Evaluation Standard and Evaluation Period depends on the system configuration and form of utilization.
For this reason, Automated Storage Tiering has prepared three types of execution modes (Auto, Semi-Auto, and Manual). The "Semi-Auto" and "Manual" execution modes may be used to test the Tiering policy without actually moving data in the target volume. Use these modes to decide the value for IOPS when controlling tiering in detail.
The following explains each of the execution modes.

Execution Mode	Details of Execution		Purpose of Selection
Execution Mode	Subject of Automated Execution According to Tiering Policy	Tasks That Require Manual Operation	Purpose of Selection
Auto	Collection and evaluation of access status data necessary for relocation of data within a volume Relocation of data within a volume	-	Selected for standard operation.
Semi-Auto	Collection and evaluation of access status data necessary for relocation of data within a volume	Confirmation of evaluation results, and as needed, relocation of data within a volume	Selected in the following cases: Used to review evaluation standards Used to select which data is to be moved.
Manual	Collection of access status data necessary for relocation of data within a volume	Evaluation of access status data Confirmation of evaluation results, and as needed, relocation of data within a volume	Selected in the following cases: Used to execute with standard values of the evaluation temporarily changed Used to determine the appropriateness of standard values

Of the access status data for moving the data within the volume, the day of the week subject to evaluation and the days to exclude from evaluation can be specified. Make a specification when configuring subjects of evaluation in detail according to tasks.
For the day of the week subject to evaluation, a day of the week that is to be a subject of the evaluation of the access status data is specified.
For the days to exclude from evaluation, days that are to not be included in the subject of evaluation of the access status data is specified.

Note

When the summer time function of the OS is effective, do not configure the time at which the switching of summer time takes place as the Automated Storage Tiering Execution Time. Doing so will prevent evaluation of the access status data and relocation of data within the volume from being performed properly.