> -----Original Message-----
> From: pcp-bounces@xxxxxxxxxxx [mailto:pcp-bounces@xxxxxxxxxxx] On
> Behalf Of Dave Brolley
> Sent: Saturday, 4 October 2014 5:38 AM
> To: pcp@xxxxxxxxxxx
> Subject: Re: [pcp] Multi-Volume Archive + Live Data Playback for PCP
Client
> Tools
>
> ...
> It now appears to me (and once again, please correct me if I am wrong!)
that
> the goal is for clients to be able to examine metrics from multiple
archives,
> each of which may have multiple volumes (already supported) and each of
> which may be arbitrarily distinct (i.e. not necessarily created by the
same
> pmlogger or even on the same machine).
Yep, but all the archives have contain data collected from the same host ...
different hosts require different contexts and different archives (or
different sets of archives)
> It also appears to me that the idea of transitioning to live metrics means
> transitioning to any arbitrary source (or sources?) of live metrics which
could
> be one (or more?) of:
>
>
> * following an active archive as it grows, similar to 'tail -f'
> * switching to an arbitrary active pmcd
>
> Until we all agree on what the ultimate goal is here (and perhaps I'm the
only
> one who is still not sure), it would seem unlikely that we can agree on an
> architecture or design. So please, correct me where I am wrong and fill in
the
> blanks where I have missed them.
>
I still see these as disjoint and independent pieces of work. There is a
use case for both at the same time, but I think this is likely to be a less
common use case. The more common use cases are
- historical analysis over a set of archives that are _not_ being actively
written
- live analysis where you want some (small) history from one archive that is
being written to provide context for on-going live reporting
Even in the less common case of combining the two, they are still disjoint
... the transition from archive to live involves only ONE archive.
So we could proceed with the archive set work which is better understood and
not subject to architectural discussion, and independently focus on the
architectural design for the transition piece which is where there is less
agreement at the moment.
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