I've got about 70 linux instances running on an OpenStack cluster that currently consists of two compute nodes and one controller. Also, these machines live in a RackSpace DC as part of their 'Private Cloud' program, so all of our resources are dedicated.
Previously we were using only RackSpace's NTP servers to synchronize the clocks on all of our instances, but Check_MK was frequently notifying us that the instances were syncing to themselves [stratum 10], implying that the NTP servers were not responding. Given that only 4/70+ instances had public IP addresses I assumed that RackSpace's NTP servers were ratelimiting us since they would be seeing 35+ times the normal rate of NTP queries originating from our two compute hosts. This seemed logical since the 4 instances with public IPs never generated any complaints about NTP.
To address this I changed ntpd.conf on our instances to include our controller node alongside the Rackspace servers so we would at least have a fallback when the RS servers stopped responding. [the NTP cookbook we are using does not allow us to set a preference] However, this has not stopped, or even reduced the number of NTP complaints. I've been seeing
last entries in
ntpq -p in excess of 60 minutes for all three hosts. I can't see how rate IP-based rate limiting might be coming into effect with the controller node since the instances and the controller reside on, and communicate through, a private network where every instance has its own IP address.
What could be causing this? As far as I've been able to tell there is nothing in the
restrict default line that would cause what we're experiencing.
ntp.conf from an instance:
driftfile /var/lib/ntp/ntp.drift statsdir /var/log/ntpstats/ leapfile /etc/ntp.leapseconds statistics loopstats peerstats clockstats filegen loopstats file loopstats type day enable filegen peerstats file peerstats type day enable filegen clockstats file clockstats type day enable server controller01.dfw.domain.com iburst restrict controller01.dfw.domain.com nomodify notrap noquery server time.dfw1.rackspace.com iburst restrict time.dfw1.rackspace.com nomodify notrap noquery server time2.dfw1.rackspace.com iburst restrict time2.dfw1.rackspace.com nomodify notrap noquery restrict default kod notrap nomodify nopeer noquery restrict 127.0.0.1 nomodify restrict -6 default kod notrap nomodify nopeer noquery restrict -6 ::1 nomodify server 127.127.1.0 # local clock fudge 127.127.1.0 stratum 10
ntp.conf from the controller node:
driftfile /var/lib/ntp/ntp.drift statsdir /var/log/ntpstats/ leapfile /etc/ntp.leapseconds statistics loopstats peerstats clockstats filegen loopstats file loopstats type day enable filegen peerstats file peerstats type day enable filegen clockstats file clockstats type day enable server 0.pool.ntp.org iburst restrict 0.pool.ntp.org nomodify notrap noquery server 1.pool.ntp.org iburst restrict 1.pool.ntp.org nomodify notrap noquery server 2.pool.ntp.org iburst restrict 2.pool.ntp.org nomodify notrap noquery server 3.pool.ntp.org iburst restrict 3.pool.ntp.org nomodify notrap noquery restrict default kod notrap nomodify nopeer noquery restrict 127.0.0.1 nomodify restrict -6 default kod notrap nomodify nopeer noquery restrict -6 ::1 nomodify server 127.127.1.0 # local clock fudge 127.127.1.0 stratum 10
- Controller node OS is Ubuntu 12.04.3 LTS running ntpd 4.2.6p3
- Instance OSes are Centos 6.4/6.5 running ntpd 4.2.4p8/4.2.6p5
# ntpq -npcrv remote refid st t when poll reach delay offset jitter ============================================================================== +18.104.22.168 22.214.171.124 2 u 933 1024 377 50.360 3.898 5.064 -126.96.36.199 188.8.131.52 2 u 372 1024 377 27.384 6.635 5.323 +184.108.40.206 220.127.116.11 2 u 780 1024 357 47.656 0.897 0.596 *18.104.22.168 22.214.171.124 2 u 373 1024 377 40.828 1.786 0.163 127.127.1.0 .LOCL. 10 l 84d 64 0 0.000 0.000 0.000 associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync, version="ntpd email@example.com Tue Jun 5 20:12:08 UTC 2012 (1)", processor="x86_64", system="Linux/3.2.0-54-generic", leap=00, stratum=3, precision=-22, rootdelay=48.228, rootdisp=69.214, refid=126.96.36.199, reftime=d6f049cf.5ce03f06 Wed, Apr 9 2014 22:35:59.362, clock=d6f04f81.183edd61 Wed, Apr 9 2014 23:00:17.094, peer=21729, tc=10, mintc=3, offset=1.514, frequency=12.879, sys_jitter=1.158, clk_jitter=0.896, clk_wander=0.058
$ ntpq -npcrv remote refid st t when poll reach delay offset jitter ============================================================================== +10.240.0.81 188.8.131.52 3 u 1997 1024 376 0.461 -2.098 0.194 +184.108.40.206 220.127.116.11 2 u 1556 1024 376 0.677 2.234 4.023 *18.104.22.168 22.214.171.124 2 u 1664 1024 376 0.793 -0.783 0.836 127.127.1.0 .LOCL. 10 l 51h 64 0 0.000 0.000 0.000 associd=0 status=06ff leap_none, sync_ntp, 15 events, stale_leapsecond_values, version="ntpd firstname.lastname@example.org Sat Nov 23 18:21:48 UTC 2013 (1)", processor="x86_64", system="Linux/2.6.32-431.5.1.el6.x86_64", leap=00, stratum=3, precision=-22, rootdelay=30.593, rootdisp=105.114, refid=126.96.36.199, reftime=d6f04951.9026bd89 Wed, Apr 9 2014 22:33:53.563, clock=d6f04fd1.0d15b2be Wed, Apr 9 2014 23:01:37.051, peer=54008, tc=10, mintc=3, offset=-0.295, frequency=-0.163, sys_jitter=1.914, clk_jitter=0.918, clk_wander=0.080, tai=35, leapsec=201207010000, expire=201306280000