Indicates a histogram of the different regions of all the LUNs in the Storage Domain by the frequency of I/O access.The histogram bar height represents the amount of data transferred. The y‑axis is not labeled.
Indicates a graph of the Storage Class and the capacity of the LUN regions for the selected auto‑tiered LUNs. The chart also shows a number that represents the QoS priority for the auto‑tiered LUN. A table at the bottom of the chart provides the list of selected LUNs. The table is also a legend for the LUNs that are represented on the graph.
The two graphs permit you to observe the placement of the data blocks and determine the effectiveness of the QoS Plus feature that is applied to the selected auto‑tiered LUNs.
Figure 1: Data Transferred By Number of Accesses histogram
1 I/O activity of the LUN region that occupies the Performance SSD | 4 I/O activity of the LUN region that occupies the Capacity HDD |
2 I/O activity of the LUN region that occupies the Capacity SSD | 5 LUN region |
3 I/O activity of the LUN region that occupies the Performance HDD |
The histogram represents the I/O distribution and the data transfer activity for all the auto‑tiered LUNs in the Storage Domain. The system counts the number of I/O accesses that was necessary to transfer data to and from the auto‑tiered LUNs. The information is then plotted on the graph from the lowest I/O activity to the highest. The system categorizes different regions of a LUN by the frequency of access and by Storage Class. The graph shows the amount of data transferred to each of these categories.
QoS Plus is most effective if the regions of the LUN that receive most of the I/O are in the best Storage Class. The graph shows that the storage is used effectively when the regions of the LUN that receive the most number of accesses are also in the most efficient Storage Class that is available, which is the Performance solid-state drives (SSDs). If the regions of the LUN with the most number of accesses are not in SSD, the performance could be improved by adding Performance SSD capacity to the Storage Domain.
Figure 2: Tier Structure by Storage Class and QoS Priority graph
1 Allocated capacity of the LUN | 5 Relative LUN storage capacity that occupies the Capacity HDD |
2 Relative LUN storage capacity that occupies the Performance SSD | 6 Tooltip |
3 Relative LUN storage capacity that occupies the Capacity SSD | 7 QoS Priority value:
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4 Relative LUN storage capacity that occupies the Performance HDD | 8 LUN Row number that corresponds to the list of LUNs below the graph |
The Storage Class of each region within the LUN
The storage capacity of each region
A value that represents the QoS priority of the LUN
The graph information helps you determine if your LUNs are placed in the optimum Storage Class and assigned the appropriate QoS priority. Ideally, you want your LUNs with heavy I/O loads and larger capacity requirements assigned to the premium Storage Class and using the highest QoS priority level. Conversely, you want the LUNs with low I/O loads assigned to the low-cost Storage Class using a low QoS priority level.
The Generate Auto‑Tier Effectiveness Report dialog allows you to view the Auto‑Tier Effectiveness report. The report summarizes the results of the analysis that the QoS Plus feature has performed on the auto‑tiered LUNs in the Storage Domain.
Approximate constrained skew value | Description |
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Is close to 100 |
Indicates that the I/O activity and that the LUN data are unevenly distributed across all the available Storage Classes. The LUN contains a small amount of data, which resides on high-cost Performance SSDs, that are receiving all the I/O activity. The same LUN also contains a majority amount of data that resides on low-cost storage, such as Capacity drives, that is never accessed. QoS Plus can benefit the LUN. |
Is close to 0 |
Indicates that the I/O activity and data are evenly distributed across all the available Storage Classes. QoS Plus can provide little benefit for the LUN. |
Indicates the number of IOPS that is averaged over the previous auto‑tier scan cycle.
Indicates the number of IOPS for a two‑minute time frame where the IOPS were the greatest during the previous auto‑tier scan cycle.