gwlmsend(1M)gwlmsend(1M)NAMEgwlmsend - send metric data to gWLM for use in a custom policy
SYNOPSISgwlmsend [-h] [-w wait_time] metric [value]
AVAILABILITY
This command is available only on gWLM managed nodes (HP-UX systems
where you run gwlmagent) in /opt/gwlm/bin/ to users logged in as root.
DESCRIPTIONgwlmsend updates values for metrics named in gWLM's custom policies.
You define these metrics by specifying them in a custom policy. gWLM
then depends on you to provide values for the metrics so it can form
resource requests based on those metric values. For example, gWLM may
compare a metric value against a target you specify and then form a
request. Alternatively, gWLM may simply scale the metric value to form
its request.
Use gwlmsend in a script or on the command line to provide either a
single metric value or a stream of values separated by white space on
standard input.
Presumably, you will use a command to collect or provide values for
your metrics. Ensure this command provides a continuous stream of met‐
rics for your custom policy's use by starting it in a boot script or by
having cron start it.
Metric-collection points are used to transfer the values for metrics to
gwlmagent. gwlmsend does not create the metric-collection points; this
is done by gwlmagent. However, gwlmsend can be told to wait for the
creation of the metric-collection point through a command-line option.
OPTIONS-h Displays usage information and exits. This option overrides all
other options.
-w wait_time
Instructs gwlmsend to wait wait_time seconds for the metric-col‐
lection point to be created before exiting. The default wait_time
is 5 seconds.
Being able to specify this delay is useful when gWLM management
starts with a system boot: You may need to give the gwlmagent dae‐
mon more time to create the metric-collection point.
metric
Specifies that the gWLM metric with the name metric is being
updated. This argument is required and must match a metric name
specified in:
+ The gWLM graphical interface in HP Systems Insight Manager, in
the Metric field for a custom policy
or in
+ The name attribute in a metric tag in an XML policy definition
used by gwlm
value
Is the value for the named metric. This numeric argument must be
the last argument on the command line. If value is not provided,
white space-separated metric values are taken from standard input
and sent to gwlmagent. Any unitless integer or floating-point
number is considered a legal metric value.
For information on the use of the metric values, see the WARNINGS
section below.
RETURN VALUEgwlmsend returns exit status 0 if no errors occur, or 1 if there are
errors.
EXAMPLE
This example shows how to define a metric in a custom policy using a
portion of a gWLM XML file and gwlmsend to communicate metric values to
gWLM. (For information on creating complete XML files for gWLM, see the
gwlmxml(4) manpage.)
First, in the XML file, we define a custom policy to keep the metric
db_tx_time at 3.5.
<dataStore>
<policyDefinition name="db_policy" type="Custom">
<cpu>
<target>3.5</target>
<metric name="db_tx_time" response="Inverse">
</metric>
</cpu>
</policyDefinition>
</dataStore>
For the metric, you must specify two items:
+ name
+ response
Valid values for response are Direct, Inverse, and Scale. With an
Inverse response, a metric value greater than the target results in a
CPU request larger than the current CPU resource allocation. If the
request produces a larger allocation for the workload, the metric
value decreases. So in this example, with an Inverse response and the
metric being a DBMS transaction time, we would expect the time to
decrease as more resources are allocated to the DBMS workload associ‐
ated with this policy. (For information on the other values for
response, see gwlmxml(4).)
Second, we use gwlmsend in either a shell script or on the command
line. If the data is coming from a file, say logfile, we can forward
the data to gWLM as follows:
tail -f logfile | gwlmsend db_tx_time
Alternatively, we can forward exactly one metric value at a time as
follows:
gwlmsend db_tx_time value
NOTE
Be careful of I/O buffering when feeding data to gwlmsend. For
example, the following line works as expected:
tail -f logfile | gwlmsend db_tx_time
However, adding awk or other utilities that buffer I/O can
result in data being delayed, or not even sent, to gwlm‐
send--depending on when the buffer is flushed:
tail -f logfile | awk '{print $1}' | gwlmsend db_tx_time
WARNINGS
I/O buffering
As indicated in the EXAMPLE section above, I/O buffering can delay the
sending of data.
Loss of updated values
If gwlmsend updates the value of a metric more than once in a gWLM
allocation interval, only the last update before the interval ended is
used by gWLM in allocating resources.
Metric values on any change to an SRD
If you make any change to an SRD, the metric value for a custom policy
for a workload based on:
+ An nPartition or virtual partition is ignored until it is updated.
gWLM tries to maintain the partition's current size until the metric
value is updated.
+ A pset or fss group is effectively reset to 0--potentially resulting
in unintended CPU resource movement. Resend metric values quickly
after making SRD changes to ensure gWLM is allocating CPU resources
as desired.
Use of outdated values
gWLM always uses the last value it received for a metric to determine
CPU allocations for the associated workload. If your command for updat‐
ing metric values has exited unexpectedly or does not update regularly,
gWLM repeatedly uses the last value it received--regardless of the
workload's current behavior.
Precision to six significant digits
gwlmsend is precise to only six significant digits. For example, if you
specify a metric value such as -12345678 with gwlmsend, the value is
interpreted as -12345700 as the ending 678 is rounded to 700.
DEPENDENCIESgwlmsend depends on gWLM to create metric-collection points. gwlmagent
is responsible for collecting the metric values from a metric-collec‐
tion point when a custom policy is defined with a metric specification
and used in a deployed SRD.
AUTHORgwlmsend was developed by HP.
FEEDBACK
If you would like to comment on the current HP gWLM functionality or
make suggestions for future releases, please send email to:
gwlmfeedback@rsn.hp.com
SEE ALSOgwlm(1M), gwlmagent(1M), gwlmxml(4), gwlm(5)gwlmsend(1M)
