Hi All,
It looks like I will be getting involved with this, so let me see if I
can summarize what I understand what has been discussed so far.
It looks like the big-picture direction of this is to allow tools to
specify a time interval for their metrics which could include archived
data and continue on into the 'live' domain without the tools needing to
be aware of where the data originated and continues to originate. That
is, a tool may want data from some starting time to some ending time or
from some starting time and continuing on into the future and the tool
should not have to be bothered with the details of which archives
contain the previous data or how how the future data will be obtained.
A unified context was suggested for local data, but seems to have been
replaced by the notion of a 'live' archive mode in which data would be
obtained across archives, if needed, and in which an active archive
would continue to be read as data is added to it, if needed. Given a
specified time window, the distinction between -h and -a becomes blurred
in this world.
Since the data may not be local, an intermediate server has been
suggested (either a new one or an extension to an existing server) which
would handle the details of where to get data for a given time period
for a given host, thus abstracting the idea of whether the data is local
or remote.
Some details of existing and previously existing tools which could read
active pmlogger archives has been given along with their caveats.
Hopefully I have it right so far.
The area in which I will be getting involved, initially, will be the
transition from archived to live data. So far, the discussion has
focused on the difficulties of reading new data from an active archive.
Maybe I missed it but the existence of an active archive suggests to me
the existence of an active pmlogger which, suggests a reachable pmcd
(perhaps via pmproxy). Has anyone suggested simply switching to
obtaining live data from the pmcd rather than trying to read data from
the active archive? Perhaps the concern was in missing a metric value
still cached in pmlogger and not yet written to the archive? I'm sure
that there would be additional synchronization issues. I just wanted to
make sure that the idea had not already been raised and dismissed.
Dave
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