On Wed, 2007-05-16 at 16:05 -0500, Matthew Chambers wrote:
> The default RRAs are set up for "hourly, daily, monthly, yearly"
> because I think those are by far the most common use cases.
Those are the most common use cases because (until recently) those were
the ONLY use cases that the web frontend supported :-)
> If those are the defaults and no custom RRAs have been specified but
> custom intervals HAVE been specified, the proper size of the RRAs can
> be reasonably calculated and compared to the existing RRAs based on
> those intervals instead of the default 15 second interval.
OK, I think I get what you are saying now. (I think I misunderstood
your original suggestion.)
The default behavior now is something like this:
if ($step not defined)
$step = 15 secs
if (no_custom_RRA)
$num_points = 244
# Define RRA for 1-hour data
RRA = "RRA:AVERAGE:0.5:1:$num_points"
This has problems if you redefine the time step, but don't redefine the
RRAs. You're suggesting something like this:
if ($step not defined)
$step = 15 secs
if (no_custom_RRA)
# Number of points needed for 1 hour of data
# (plus some wiggle room)
$num_points = (3600 / $step) + 4
# Define RRA for 1-hour data
RRA = "RRA:AVERAGE:0.5:1:$num_points"
In essence, you want a dynamically determined default RRA instead of a
static one. That makes sense. As long as gmetad doesn't change
existing RRAs automaically, this type of modification shouldn't present
a problem. (At least as far as I can see.)
--
Rick Mohr
Systems Developer
Ohio Supercomputer Center
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