Logical volumes
Logical volume usage statistics provide information about the load on storage managed by HCP. These statistics are available only for individual logical volumes. HCP reports logical volume usage statistics in these graphs:
LUN Read/Write
This graph shows the number of blocks read from the logical volume per second and the number of blocks written to the logical volume per second.
LUN Utilization
This graph shows the usage of the communication channel between the operating system and the logical volume as a percent of the channel bandwidth.
The way logical volumes are used depends on the HCP system configuration. Some logical volumes can store only objects, some can store only the metadata query engine index, and some can store both. Additionally, in an HCP SAIN system, some logical volumes may used for spindown storage. How you interpret the statistics in the logical volume usage graphs is partly dependent on the these factors.
High read, write, and access values for all logical volumes along with low CPU usage may mean that the HCP system storage has insufficient bandwidth to support its workload. In this case, you may need to add storage to the system to spread read and write operations across more logical volumes.
High read and write rates for some but not all logical volumes may mean that the distribution of objects across the nodes in the system is uneven. To verify that this is the case, check the logical volume usage statistics on the Hardware page in the System Management Console. To resolve the issue, submit a request to your authorized HCP service provider to run the Capacity Balancing service to bring the object distribution to a more balanced state.