Owners Manual

Best Practices: Performance and Monitors | Performance Monitoring
OMNM 6.5.2 User Guide 441
Best Practices: Performance and Monitors
Monitoring can impact system performance. Monitors with many targets, many attributes per
target and frequent polling intervals are most likely to slow system performance.
CAUTION:
Limit monitor targets to 10,000 or less per monitor (distribute them if you have more than 10,000). The
following suggests other ways to improve monitor performance, too.
The following are the primary considerations when configuring monitors to get the desired
performance from your system:
Database Insertion Rate — How many rows can your hardware realistically insert per second?
Every system has a maximum data insertion rate. This rate depends on the system’s hardware
configuration. A standard 7200 RPM disk can typically manage 300 insertions per second per
disk. 10000-15000 RPM disk can have as many as 600 insertions per second per disk. Your
experience may vary depending on your drive’s controller and configuration.
The sum of all monitors’ insertion rate should not exceed the system’s maximum data
insertion rate. To calculate the insertion rate of a monitor apply the following formula:
<# of monitor targets> x <# of retained attributes>/<polling interval in seconds> =
inserts /second.
So a monitor with 100 targets, retaining 10 attributes once a minute would have an insertion
rate of 17 rows per second (100 * 10 / 60 = 16.67 inserts per second).
Example:
Monitor A : 1000 targets * 10 retained attributes each / 120 = 83 insert per second
Monitor B : 100 targets * 25 retained attributes each / 600 = 4 insert per second
Monitor C: 10000 targets * 10 retained attributes each / 60 = 1667 insert per second
System total insertion rate (A+B+C) : 1754 insertions per second
This configuration would be too aggressive for a system with a 7200 RPM disk since it dramatically
exceeds the 300 insertions per second that the disk can support.
The following alternatives could resolve this:
• Upgrade to disk hardware that can keep up with the insertion rate. If the target insertion rate
is 1754 inserts per second, add a disk to the array. If 1754 inserts / 300 insertions per second on
a 7200 rpm disk amounts to 5.84 disks, use 6 disks (or more). If using 15000 RPM disks at 600
inserts per second, 1754/600 means you need 2.92 (3 discs) minimum.
• Modify the monitors to achieve a lower insertion rate. If you only have one 7200 RPM disk, it
can only support 300 insertions per second. You have the option of lowering the target count,
reducing what is retained or lengthening the polling interval.
So from the example above if we changed the polling interval from once a minute to once
every 10 minutes, Monitor C’s insertion rate would drop to 167 inserts per second. The overall