Why Is There No Block Device Usage Metric for One of the Two Disks on a Server?

Symptom

When you view the disk I/O metrics on the Cloud Eye console, two disks vda and vdb are displayed. The block device usage metric is available for vda but not for vdb.

Possible Causes

If a disk is not attached to a mount point, the block device usage of the disk will not be collected. In the following figure, the vdb disk is not attached.

Procedure

1. Attach the disk to a mount point.

2. Verify that the block device usage can be collected.