•
Different virtual disks have higher usage at different times of day.
Load balancing
A load balance policy is used to determine which path is used to process I/O. Multiple options for setting the load balance policies let you
optimize I/O performance when mixed host interfaces are configured.
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
Performance Monitor allows you to track a storage array’s key performance data and identify performance bottlenecks in your system. You
can use Performance Monitor to perform these tasks:
•
View in real time the values of the data collected for a monitored device. This capability helps you to determine if the device is
experiencing any problems.
•
Identify when a problem started or what caused a problem by seeing a historical view of a monitored device.
•
Specify the performance metric and the objects that you want to monitor.
•
View data in tabular format (actual values of the collected metrics) or graphical format (as line graphs), or export the data to a file.
Three types of performance monitoring exist:
•
Real-time graphical
—Plots performance data on a graph in near real time.
•
Real-time textual
—Shows performance data in a table in near real time.
•
Background (historical)
—Plots graphical performance data over a longer period. You can view background performance data for a
session that is currently in progress or for a session that you previously saved.
This table shows some specific characteristics of each type of performance monitoring:
Table 3. Characteristics of different types of performance monitoring
Type of
Performance
Monitoring
Sampling Interval
Length of Time
Displayed
Maximum Number
of Objects Displayed
Ability to Save Data How Monitoring
Starts and Stops
Real-time graphical
5 sec
5 min rolling window
5
No
Starts automatically
when AMW opens.
Stops automatically
when AMW closes.
Real-time textual
5-3600 sec
Most current value
No limit
Yes
Starts and stops
manually. Also stops
About your MD Series storage array
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