1. Confirm the performance of pools and DP-VOLs

Using Performance Monitor, confirm the performance of pools and DP-VOLs. If the performance of pools and DP-VOLs is poor, go to Step 2.

2. Confirm the Dynamic Tiering setting

Using Device Manager - Storage Navigator or Command Control Interface, confirm the Dynamic Tiering setting. If the values are set but do not conform to the design of pools or LDEVs, change the settings. If the values are set and conform to the design of pools or LDEVs, go to Step 3.

3. Confirm and improve the progress of tier relocation processing

Confirm the progress of tier relocation processing in Completed Rate (%) in the tier relocation log file. If the progress of the tier relocation process is low, there might be many pages where the page allocation is not optimized. In this case, change the Monitoring Mode or Cycle Time setting. The recommended values are as follows:

Monitoring Mode: If Period Mode is set, change to Continuous Mode.

Cycle Time: Set a longer period than the current setting.

If the recommended values are already set or if the progress of tier relocation processing is still low even after the settings are changed, go to Step 4.

4. Confirm Performance Utilization of each tier

You can confirm the performance utilization of each tier in the View Tier Properties window or with the raidcom get dp_pool command. The performance utilization is the ratio (%) of the number of I/Os against the performance potential of the tier. For example, if the performance utilization is 90% or more, a workload greater than the processing capacity of the tier is being applied to the tier.

If Performance Utilization is 90% or more on one or more of the tiers, or if Performance Utilization is 60% on all tiers, add drives and expand the pool capacity.

1. In the case that Performance Utilization is 90% or more on a tier:

Add drives to the tier where Performance Utilization is 90% or more and confirm the usage ratio of the capacity. The recommended drives to be added are as follows:

Drives to be added to the tier where Performance Utilization is 90% or more	Recommended pool volumes to be added
SSD	Add SSD pool volumes.
SAS10K or SAS15K	If the performance is given greater priority than the bit-cost: Add SSD pool volumes. If the bit-cost is given greater priority than the performance: Add SAS10K or SAS15K pool volumes. However, add SSD pool volumes if the capacity utilization of the SAS tier (SAS10K or SAS15K) is low.
SAS7.2K	If the performance is given greater priority than the bit-cost: Add SAS (SAS10K or SAS15K) pool volumes. If the bit-cost is given greater priority than the performance: Add SAS7.2K pool volumes. However, add SAS (SAS10K or SAS15K) pool volumes if the capacity utilization of the SAS 7.2K tier is low.

2. In the case that Performance Utilization is 90% or more on two or more tiers:

a. Collect the frequency distribution on the View Tier Properties window.

b. From the frequency distribution and the performance limit of each tier, seek the ratio of the most suitable tier capacity.

The performance limit of tier 2 is the maximum average IOPH on one page that the drive related to tier 2 can process. The performance limit of tier 3 is the maximum average IOPH on one page that the tier 3 drive can process. Based on these values, calculate the most suitable tier capacity for the tier 1, tier 2, and tier 3.

The most suitable tier capacity for tier 1: The capacity from 0 GB to the capacity related to the performance limit of tier 2

The most suitable tier capacity for tier 2: The capacity from the performance limit of tier 2 to tier 3 of that capacity.

The most suitable tier capacity for tier 3: The capacity from the performance limit of tier 3 to the maximum capacity of tier 3

Then, based on the most suitable tier capacity for each tier, calculate the most suitable capacity ratio of tier 1, tier 2, and tier 3 as follows:

The most suitable tier capacity for tier 1 : The most suitable tier capacity for tier 2 : The most suitable tier capacity for tier 3

c. Compare the ratio of the real tier capacity to the ratio of the most suitable tier capacity.

Comparing the ratio of tier capacity	Pool volumes suggested to be added
The ratios of the most suitable tier capacity and real tier capacity are different.	Add pool volumes to the tier that is lacking capacity.
The ratios of the most suitable tier capacity and real tier capacity are the same.	If the performance is given greater priority than the bit-cost: Add SSD or SAS (SAS10K or SAS15K) pool volumes. If the bit-cost is given greater priority than the performance: Add SAS (SAS10K or SAS15K) pool volumes. However, add SSD pool volumes if the capacity utilization of the SAS tier (SAS10K or SAS15K) is low.

d. Add drives and expand the pool capacity.

3. In the case that Performance Utilization is 60% on all tiers:

Add drives in the upper tier and expand the pool capacity.