Dell POWERVAULT MD3600I - Manual (Page 32)

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.
You can choose from the following:
– RAID controller modules
– Virtual disks
– Storage array totals
4. Adjust Polling interval to set how often you want to update the performance statistics.
NOTE: For an accurate elapsed time, do not use the Synchronize RAID controller module Clocks option while
using the Performance Monitor.
NOTE: Each time the polling interval elapses, the Performance Monitor queries the storage array again and
updates the statistics in the table.
5. If required, click OK to go back to the Performance Monitor window.
6. Click Start.
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