Dell PowerVault MD3820f - Manual (Page 35)

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 when
View Real-time
Textual
Performance
Monitor dialog
closes or AMW
closes.
Background 10 min 7 day rolling
window
5 Yes Starts and stops
manually. Also
stops when
EMW closes or
firmware
download
starts.
Keep these guidelines in mind when using Performance Monitor:
• Each time the sampling interval elapses, the Performance Monitor queries the storage array again and
updates the data. The impact to storage array performance is minimal.
• The background monitoring process samples and stores data for a seven-day time period. If a
monitored object changes during this time, the object will not have a complete set of data points
spanning the full seven days. For example, virtual disk sets can change as virtualDisks are created,
deleted, mapped, or unmapped or physical disks can be added, removed, or failed.
• Performance data is collected and displayed only for an I/O host visible (mapped) virtual disk, a
snapshot group repository virtual disk, and a consistency group repository virtual disk. Data for a
snapshot (legacy) repository virtual disk or a replication repository virtual disk is not collected.
• The values reported for a RAID controller module or storage array might be greater than the sum of
the values reported for all of the virtual disks. The values reported for a RAID controller module or
storage array include both host I/Os and I/Os internal to the storage array (metadata reads and writes),
whereas the values reported for a virtual disk include only host I/O
Interpreting Performance Monitor Data
Performance Monitor provides you with data about devices. You can use this data to make storage array
performance tuning decisions, as described in the following table.
Performance Data Implications for Performance Tuning
Total I/Os This data is useful for monitoring the I/O activity of
a specific RAID controller module and a specific
virtual disk, which can help identify possible high-
traffic I/O areas.
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