Tier monitoring and relocation cycles
Performance monitoring and tier relocation can be set to execute in one of two execution modes: Auto and Manual. You can set up execution modes, or switch between modes by using either Device Manager - Storage Navigator or Command Control Interface.
In Auto execution mode, monitoring and relocation are continuous and automatically scheduled. In Manual execution mode, the following operations are initiated manually.
Start monitoring
Stop monitoring and recalculate tier range values
Start relocation
Stop relocation
In both execution modes, relocation of data is automatically determined based on monitoring results. The settings for these execution modes can be changed nondisruptively while the pool is in use.
Auto execution mode
Auto execution mode performs monitoring and tier relocation based on information collected by monitoring at a specified constant frequency: 0.5, 1, 2, 4, or 8 hours. All Auto execution mode cycle frequencies start at midnight (00:00). For example, if you select a 1 hour monitoring period, the starting times would be 00:00, 01:00, 02:00, 03:00, and so on.
As shown in the following table, the 24-hour monitoring cycle allows you to specify the times of day to start and stop performance monitoring. The 24-hour monitoring cycle does not have to start at midnight. Tier relocation begins at the end of each cycle. For more information, see Edit Pools window.
|
Monitoring cycle (hours) |
Start Times |
Finish Times |
|---|---|---|
|
0.5 |
0.5 hours from 00:00 AM. For example 00:00, 00:30, and 01:00 |
0.5 hours after the start time |
|
1 |
1 hour from 00:00 AM. For example 00:00, 01:00, and 02:00 |
1 hour after the start time |
|
2 |
2 hours from 00:00 AM. For example 00:00, 02:00, and 04:00 |
2 hours after the start time |
|
4 |
4 hours from 00:00 AM. For example 00:00, 04:00, and 08:00 |
4 hours after the start time |
|
8 |
8 hours from 00:00 AM. For example 00:00, 08:00, and 16:00 |
8 hours after the start time |
|
24 (monitoring time period can be specified) |
Specified time |
Specified time |
If the setting of the monitoring cycle is changed, performance monitoring begins at the new start time. The collection of monitoring information and tier relocation operations already in progress is not interrupted when the setting is changed.
Example 1: If the monitoring cycle is changed from 1 hour to 4 hours at 01:30 AM, the collection of monitoring information and tier relocation in progress at 01:30 AM continues. At 02:00 AM and 03:00 AM, however, monitoring information is not collected and tier relocation is not performed. From 04:00 AM, the collection of monitoring information and tier relocation operations are restarted. These operations are then performed at 4-hour intervals.
Example 2: If the monitoring cycle is changed from 4 hours to 1 hour at 01:30 AM, the collection of monitoring information and tier relocation in progress at 01:30 AM continues. From 04:00 AM, the collection of monitoring information and tier relocation operations are restarted. These operations are then performed at 1-hour intervals.
Collection of monitoring data to tier relocation workflow in Auto execution mode
In auto execution mode, the collection of monitoring data and tier relocation operations is performed in parallel in the next cycle. Data from these parallel processes are stored in two fields:
Data while monitoring is in progress in the next cycle.
Fixed monitoring information used in the tier relocation.
Manual execution mode
You can start and stop performance monitoring and tier relocation at any time. Keep the duration of performance monitoring to less than 7 days (168 hours). If performance monitoring exceeds 7 days, monitoring stops automatically.
Manual execution mode manages monitoring and relocation when the command is issued. You can use scripts to manage tasks based on a schedule for each day of the week.
In manual execution mode, the next monitoring cycle can be started with the collection of monitoring data and tier relocation operations performed in parallel. Data from these parallel processes are stored in two separate fields:
Data while monitoring is in progress in the next cycle.
Fixed monitoring information used in the tier relocation.
Collection of monitoring data to tier relocation workflow in manual execution mode
Case 1: If the second collection of the monitoring information finishes during the first tier relocation, the latest monitoring information is the second collection. In that case, the first collection of monitoring information is referenced only after the first tier relocation completes.
Second collection of monitoring information finishes before the first tier relocation completes
Case 2: When tier relocation is performed with the first collection of monitoring information, the second collection of monitoring information can be performed. However, the third collection cannot start. Because only two fields store collected monitoring information, the third collection cannot be overwritten.
In that case, the third collection of the monitoring information starts after the first tier relocation stops or tier relocation completes.
Monitoring information also does not start under these conditions:
When the second tier relocation is performed, the fourth collection of monitoring information cannot start.
When the third tier relocation is performed, the fifth collection of monitoring information cannot start.
If such conditions exist, two cycles of monitoring information cannot be collected continuously while tier relocation is performed.
Third collection of monitoring information while tier relocation is performed
