Re: [chrony-dev] Retention of sources' measurement history

[Vincent Blut <vincent.debian@xxxxxxx>]

Hi Bill,

Sorry for the delay in answering, I’ve been absorbed by high priority 
things and ended up forgetting about this thread.

> On Sat, Aug 27, 2016 at 01:20:13PM -0700, Bill Unruh wrote:
> > On Sat, 27 Aug 2016, Vincent Blut wrote:
> >
> > Hi,
> >
> > Currently, the measurement history is persistent for each sources no 
> > matter if it is inspected by chronyd afterward. This persistence 
> > might cause some staled measurements. Thus, I think it would be nice 
> > to have a clean way (meaning not having to write a shell script ;-) 
> > ) to deal with those old measurements. So, what about implementing a 
> > dedicated chronyc option (or passing an option to the dump command) 
> > to manage that task?
> >
> > Have a good week-end,
> > Vincent
>
> I think you might havee to be a bit more detailed in describing what 
> the problem is that you feel is occuring.
> Which old measurements?

In case that wasn’t clear enough from my previous message, I’m talking 
about measurements written by “chronyc dump” or the “dumponexit” 
directive. Here is a preview from those staled measurements from a test 
system where I set the “dumponexit” directive.

$LC_TIME=C ls -ltr /var/lib/chrony/*.dat | tr -s ' ' | cut -d ' ' -f 6,7,9
May 28 /var/lib/chrony/178.33.111.48.dat
May 28 /var/lib/chrony/178.32.217.126.dat
May 28 /var/lib/chrony/212.83.187.62.dat
May 28 /var/lib/chrony/37.187.104.44.dat
May 28 /var/lib/chrony/212.47.239.163.dat
May 28 /var/lib/chrony/212.83.128.217.dat
May 28 /var/lib/chrony/37.59.119.229.dat
May 28 /var/lib/chrony/37.187.107.140.dat
May 28 /var/lib/chrony/188.165.199.222.dat
May 28 /var/lib/chrony/178.33.111.47.dat
May 29 /var/lib/chrony/91.121.157.10.dat
May 29 /var/lib/chrony/62.4.12.66.dat
May 29 /var/lib/chrony/193.17.192.211.dat
Jun 1 /var/lib/chrony/195.154.216.44.dat
Jun 1 /var/lib/chrony/91.121.154.174.dat
Jun 1 /var/lib/chrony/188.165.201.225.dat
Jun 8 /var/lib/chrony/37.59.60.67.dat
Jun 8 /var/lib/chrony/129.250.35.251.dat
Jun 8 /var/lib/chrony/91.121.209.8.dat
Jun 8 /var/lib/chrony/37.187.56.220.dat
Jun 23 /var/lib/chrony/188.165.250.19.dat
Jun 27 /var/lib/chrony/46.105.237.136.dat
Jun 27 /var/lib/chrony/212.83.179.156.dat
Jun 27 /var/lib/chrony/194.177.34.115.dat
Jun 30 /var/lib/chrony/78.192.88.115.dat
Jun 30 /var/lib/chrony/178.32.216.71.dat
Jun 30 /var/lib/chrony/37.187.5.167.dat
Jul 4 /var/lib/chrony/5.135.183.146.dat
Jul 4 /var/lib/chrony/195.154.176.80.dat
Jul 4 /var/lib/chrony/80.74.64.2.dat
Jul 4 /var/lib/chrony/213.246.39.118.dat
Jul 4 /var/lib/chrony/195.154.113.163.dat
Jul 5 /var/lib/chrony/178.33.227.201.dat
Jul 5 /var/lib/chrony/163.172.195.230.dat
Jul 7 /var/lib/chrony/5.149.182.30.dat
Jul 7 /var/lib/chrony/5.135.3.88.dat
Jul 10 /var/lib/chrony/92.222.82.98.dat
Jul 10 /var/lib/chrony/91.121.139.186.dat
Jul 10 /var/lib/chrony/37.187.7.160.dat
Jul 10 /var/lib/chrony/151.80.124.104.dat
Jul 14 /var/lib/chrony/163.172.35.115.dat
Jul 14 /var/lib/chrony/151.80.196.50.dat
Jul 14 /var/lib/chrony/194.57.169.1.dat
Jul 14 /var/lib/chrony/95.81.173.74.dat
Jul 14 /var/lib/chrony/5.196.192.58.dat
Aug 15 /var/lib/chrony/94.23.217.75.dat
Aug 15 /var/lib/chrony/91.134.227.51.dat
Aug 15 /var/lib/chrony/178.32.80.7.dat
Aug 15 /var/lib/chrony/176.31.102.171.dat
Aug 15 /var/lib/chrony/95.81.173.155.dat
Aug 15 /var/lib/chrony/91.121.165.146.dat
Aug 16 /var/lib/chrony/5.196.160.139.dat
Aug 16 /var/lib/chrony/195.154.71.176.dat
Aug 16 /var/lib/chrony/195.154.189.15.dat
Aug 24 /var/lib/chrony/51.255.119.22.dat
Aug 24 /var/lib/chrony/193.52.136.2.dat
Aug 24 /var/lib/chrony/176.31.251.139.dat
Aug 24 /var/lib/chrony/94.23.210.194.dat
Aug 24 /var/lib/chrony/94.23.0.110.dat
Aug 24 /var/lib/chrony/164.132.59.13.dat
Sep 3 /var/lib/chrony/151.80.168.4.dat
Sep 3 /var/lib/chrony/92.222.227.225.dat
Sep 3 /var/lib/chrony/195.154.216.35.dat
Sep 3 /var/lib/chrony/195.154.174.209.dat
Sep 13 /var/lib/chrony/51.255.197.148.dat
Sep 13 /var/lib/chrony/212.83.158.83.dat
Sep 13 /var/lib/chrony/129.250.35.250.dat
Sep 17 /var/lib/chrony/95.81.173.8.dat
Sep 17 /var/lib/chrony/5.135.188.53.dat
Sep 17 /var/lib/chrony/195.154.10.106.dat
Sep 26 /var/lib/chrony/91.224.149.41.dat
Sep 26 /var/lib/chrony/91.134.209.213.dat
Sep 26 /var/lib/chrony/188.165.240.21.dat
Sep 26 /var/lib/chrony/188.165.224.26.dat
Oct 1 /var/lib/chrony/212.85.158.10.dat
Oct 1 /var/lib/chrony/195.154.41.195.dat
Oct 1 /var/lib/chrony/163.172.10.91.dat
Oct 1 /var/lib/chrony/151.80.19.218.dat

As you can see that leaves the dump directory full of useless 
measurements, especially if one uses a pool of time servers.

> What would cause them to go stale and why would that be a problem?

Per se that does not cause any cumbersome issue… apart from wasting disk 
space.

Cheers,
Vincent

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