Diagnosing a Bad Physical Disk Layout

A non-optimal physical disk layout can cause one single physical disk to become the bottleneck of a SAN. To verify that the I/Os are well-balanced across all physical disks you can check the ReadByteRate and WriteByteRate parameters of each physical disk and make sure they have similar average values.

Verifying a Physical Disk Layout

1.	In the console, double-click the WriteByteRate parameter of the first disk for which you need to compare the activity. A graph is automatically displayed in the graph pane.

2.	Select the WriteByteRate parameter of the second disk and drag it from the tree view of the Operator tab to the graph. The second parameter is automatically added to the first one to facilitate the comparison. Repeat this operation for any other disk.

GRAPH_Disk_ReadByte_Comparison

Comparing Several Physical Disks WriteByteRate Parameters