Meta Volumes Test

Metavolumes can be created from a disk volume, stripe volume, slice volume, or another metavolume. A file system is created on the metavolume. All information stored within a metavolume is arranged in addressable logical blocks and is organized in a sequential, end-to-end fashion. A metavolume is required to create a file system because metavolumes provide the expandable storage capacity needed to dynamically expand file systems. A metavolume also provides a way to form a logical volume larger than a single disk.

Where metavolumes are in use, a slowdown or space-crunch experienced by a single metavolume, can ripple and affect the overall performance of the VNX storage system. This is why, it is imperative that metavolumes are continuously monitored for performance faults, and faults detected in the process are corrected in time to ensure uninterrupted functioning of the storage system as a whole. For this purpose, administrators can use the Meta Volumes test. This test auto-discovers the metavolumes configured on the EMC VNX Storage system, monitors the processing ability of each metavolume, and reports the following:

• Is I/O load uniformly balanced across all metavolumes, or is any metavolume overloaded?
• Are the metavolumes able to process the I/O requests quickly? Is any metavolume experiencing processing bottlenecks?

Target of the test : An EMC VNX Unified Storage system

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each meta volume in the EMC VNX Unified Storage system.

Configurable parameters for the test

Parameter	Description
Test Period	How often should the test be executed.
Host	The IP address of the storage device for which this test is to be configured.
Controller Station IP	The Control Station is the management station for the VNX for File system, and enables control and configuration of the system. The eG agent uses the CLI that runs on the Control Station to monitor and manage the performance of the VNX for File system. To enable the eG agent to use this CLI, specify the IP address of the Control Station in the Controller Station IP text box. By default, the IP address of the host will be displayed here.

Measurements made by the test

Measurement	Description	Measurement Unit	Interpretation
Read operations	Indicates the rate at which the read operations were performed on this metavolume.	Ops/Sec	A high value is desired for this measure. A consistent decrease in this value could indicate a processing bottleneck.
Write operations	Indicates the rate at which write operations were performed on this disk volume.	Ops/Sec
Read request	Indicates the rate at which the read requests were processed by this metavolume.	Requests/Sec	A consistent decrease in the value of these measures for a metavolume indicates an I/O processing bottleneck.
Write request	Indicates the rate at which the write requests were processed by this metavolume.	Requests/Sec
Data read	Indicates the rate at which data is read from this metavolume.	KiB/Sec	A consistent decrease in the value of these measures for a metavolume indicates an I/O processing bottleneck.
Data written	Indicates the rate at which data is written to this metavolume.	KiB/Sec
Average read data	Indicates the amount of data read from this metavolume per request.	KB/Request	A consistent decrease in the value of these measures for a metavolume indicates an I/O processing bottleneck.
Average write data	Indicates the amount of data written to this disk volume per request.	KB/Request
Percentage of total ops for reads	Indicates the percentage of total I/O operations on this metavolume that were read operations	Percent	In the event of an overload, you can compare the value of these measures for a metavolume to figure out what caused the overload – i.e., what type of operations were too many on the metavolume – read operations or write operations?
Percentage of total ops for writes	Indicates the percentage of total I/O operations on this metavolume that were write operations.	Percent