Setting upper-limit values for non-prioritized WWNs: many-to-many connections

After you analyze traffic statistics about prioritized WWNs and non-prioritized WWNs, you must set upper limit values to I/O rates or transfer rates for non-prioritized WWNs. Upper limit values for I/O rates are used to suppress the number of I/Os from the low priority host servers and thus provide better performance for high-priority host servers. Upper limit values for transfer rates are used to suppress the amount of data that should be transferred between the storage system and the low priority ports, thus providing better performance for high-priority host servers.

When you set an upper limit for the first time, it is recommended that the upper limit be approximately 90 percent of the peak traffic.

To set the same upper limit value to more than one non-prioritized WWN, use an SPM group. For details on SPM groups, see Working with SPM groups.

You cannot set the upper-limit value of a host bus adapter that is contained in an SPM group. The upper limit value of a host bus adapter in an SPM group is defined by the SPM group settings. For details, see Setting an upper-limit value to HBAs in an SPM group.

If an upper limit of the non-prioritized WWN is set to zero or nearly zero, I/O performance might be lowered. If I/O performance is lowered, the host cannot be connected to the storage system in some cases.

Prerequisites

Required role: Storage Administrator (System Resource Management)

The Device Manager - Storage Navigator secondary window must be enabled.

Procedure

Display the Performance Monitor window.

In Device Manager - Storage Navigator:

Select Analytics in Explorer.

Select Performance Monitor in the tree to open the Performance Monitor window.

In Command Suite:

Select the Resources tab, and expand the Storage Systems tree.

Right-click the target storage system and then select Performance Monitor.

In the Performance Monitor window, click Server Priority Manager to open the Server Priority Manager window.

Click to change to Modify mode.

In the Server Priority Manager window, click Server Priority Manager. The Server Priority Manager main window appears.

Ensure that the WWN tab is displayed.

Do one of the following:

To limit the I/O rate of the non-prioritized WWN, select IOPS from the list at the upper left corner.

To limit the transfer rate of the non-prioritized WWN, select MB/s from the list at the upper left corner.

In the upper-left tree, click the icon of the port whose traffic you want to limit below the Storage System folder.

The information about the host bus adapters which connect to the selected port is displayed in the list.

Locate the non-prioritized WWN in the list.

The Attribute column of the list indicates whether WWNs are prioritized or non-prioritized. The Attribute column of a non-prioritized WWN displays Non-Prio.

If you cannot find any non-prioritized WWN in the list, check the list at the top right corner of the window. If the list displays Prioritize, select All or Non-Prioritize.

Do one of the following:

To limit the I/O rate of the non-prioritized WWN, double-click the desired cell in the IOPS column in Upper. Next, enter the upper limit value in the cell.

To limit the transfer rate of the non-prioritized WWN, double-click the desired cell in the MB/s column in Upper. Next, enter the upper limit value in the cell.

In the list, either of the IOPS cells or MB/s cells are activated depending on the rate you specified in step 6. You can specify the limit value by using either of the I/O rate or transfer rate for each host bus adapter. The upper limit value that you entered is displayed in blue. It is allowed that you specify upper limit values by using the I/O rate for some host bus adapters and specify them by using the transfer rate for the other host bus adapters.

If one host bus adapter is connected to multiple ports and you specify an upper limit value of the host bus adapter for one port, the specified upper limit value will be applied to the host bus adapter settings for other connected ports automatically.

Click Apply to apply the settings to the storage system.

The upper limit value that you entered turns black.