Cache; About Cache - HPE XP7 User Manual

Cache

I want to ...
• Plot charts on page 30
• Start/Stop real-time performance data
collection
• View trending graphs
• View forecasting graphs
• Save template charts
• Save charts as PDF or CSV files
• Email charts as PDF/CSV

About Cache

The cache function optimizes the process of XP7, P9500, and XP disk arrays. The logical partitioning of
the cache is performed at a storage-level by dividing the cache into multiple CLPRs to reduce I/O
workload. However, performance issues can still occur. PA performs detailed monitoring of the cache
component for various performance and utilization capacities of cache, and provides historical and real-
time plotting of the collected data.
You can access the Cache screen using the main menu, or drill down from the Overview dashboard. The
status of cache is based on the default value that you have set for the Cache Usage and Cache Write
Pending metrics. If at any point the data points for the metrics exceeds the defined threshold limit for the
specified threshold duration, then the array as well as the component is flagged as critical in the Overview
and the Component levels of dashboards. For example, if the data points for the Cache Usage or Cache
Write Pending metrics exceeds the defined threshold value at least once, then the array as well as the
cache is flagged as critical in the Cache Write Pending section in the Component widget in the
Overview dashboard. You can determine the cause of this performance bottleneck by clicking on the
critical icon. The Component dashboard is displayed with all the arrays that PA monitors in the master
pane. In the Cache section in the detail pane, click the critical icon.
Alternatively, click the title of the bar charts Cache Write Pending by CLPRs and the Cache Size and
Avg Cache Usage by CLPRs. You can also click on an individual bar in the bar chart depicting a critical
component. The height of each bar depicts certain metrics. For example, the pair of bars in Cache Write
Pending by CLPRs displays the Avg and Max Write Pending details of the critical cache record.
The Cache screen displays the critical components sorted on top of the master pane. From the master
pane, select one or more cache records for which you want to plot data. By default, the Chart View area
in the detail pane displays the historical data for the last one hour. If the Cache Writes Pending Util or
the Cache Usage Util metrics have crossed the default value that you have set, it indicates of usage and
performance issues in the cache component.
The associated array components for cache are RAID Groups and Processors. You can also monitor the
performance of the associated components using the Actions menu.
To eliminate performance issues in advance, use templates that provide an at-a-glance information on the
behavior of critical components and metrics. You can also monitor real-time data, plot trend values for all
the charts, and plot forecast lines for critical metrics to predict behavior within a specified time frame.
180 Cache
Learn more
• About Cache on page 180
• Cache screen details on page 181