Monitoring System Performance; Monitoring Performance Using The Tabular View - Dell PowerVault MD3260i Administrator's Manual

You can choose one of these load balance policies to optimize I/O performance:
• Round-robin with subset — The round-robin with subset I/O load balance policy routes I/O requests, in rotation,
to each available data path to the RAID controller module that owns the virtual disks. This policy treats all paths
to the RAID controller module that owns the virtual disk equally for I/O activity. Paths to the secondary RAID
controller module are ignored until ownership changes. The basic assumption for the round-robin policy is that
the data paths are equal. With mixed host support, the data paths may have different bandwidths or different
data transfer speeds.
• Least queue depth with subset — The least queue depth with subset policy is also known as the least I/Os or
least requests policy. This policy routes the next I/O request to a data path that has the least outstanding I/O
requests queued. For this policy, an I/O request is simply a command in the queue. The type of command or the
number of blocks that are associated with the command are not considered. The least queue depth with subset
policy treats large block requests and small block requests equally. The data path selected is one of the paths in
the path group of the RAID controller module that owns the virtual disk.
• Least path weight with subset (Windows operating systems only) — The least queue depth with subset policy is
also known as the least I/Os or least requests policy. This policy routes the next I/O request to a data path that
has the least outstanding I/O requests queued. For this policy, an I/O request is simply a command in the queue.
The type of command or the number of blocks that are associated with the command are not considered. The
least queue depth with subset policy treats large block requests and small block requests equally. The data path
selected is one of the paths in the path group of the RAID controller module that owns the virtual disk.

Monitoring System Performance

You can use the Performance Monitor to select virtual disks and RAID controller modules to monitor or to change the
polling interval.
Keep these guidelines in mind when using the Performance Monitor:
• The Performance Monitor does not dynamically update its display if any configuration changes occur while the
window is open. You must close the Performance Monitor window and reopen it for the changes to be
displayed.
• Using the Performance Monitor to retrieve performance data can affect the normal storage array performance
depending on the polling interval that you set.
• If the storage array you are monitoring begins in or transitions to an unresponsive state, an informational dialog
is displayed. The dialog informs you that the Performance Monitor cannot poll the storage array for performance
data.
You can view data for select virtual disks and RAID controller modules in tabular format or in graphical format.
• Table view — The data is presented in a tabular format. For more information on the data presented in the table,
see the online help.
• Graphical View — The data is presented with a single x-axis and a single y-axis. The x-axis represents the time
for which you selected to view performance data. The y-axis represents the metric you selected on the Define
Graph window. A curve on the graph represents the value of the metric over time for a particular device. A
historical graph can contain up to four curves. A real-time graph is limited to a single curve. For the real-time
data graph, the data points refresh every 5 seconds. The system drops the oldest data point from the graph and
adds the newest data point to the graph. For historical data graphs, the data points are static.

Monitoring Performance Using The Tabular View

To monitor the performance of the arrays using the tabular view:
1. In the AMW, select Monitor → Health → Monitor Performance → Table View.
The Performance Monitor window is displayed.
2. Click Settings.
3. Select the items that you want to monitor.
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