progress, i think. thanks to all for comments. referencing,
http://www.novell.com/communities/node/8629/time-synchronization-xen-setup http://www.linux.org.za/Lists-Archives/glug-tech-0905/msg00271.html http://www.gossamer-threads.com/lists/linux/kernel/1039416 i've decoupled DomU's time service from Dom0, @ both Dom0 & DomU cat /proc/sys/xen/independent_wallclock 1 checking available kernel clocksources, cat /sys/devices/system/clocksource/clocksource0/available_clocksource xen jiffies @ Dom0's /boot/grum/menu.lst, i've added, module /vmlinuz-xen ... clocksource=jiffies ... and, at DomU's .cfg in Dom0, extra = '... clocksource=jiffies ...' verifying in both Dom0 & DomU, i've cat /sys/devices/system/clocksource/clocksource0/current_clocksource jiffies i've removed any pool servers, specifying local/regional Stratum 2/1 server, instead. both DomU & Dom0 have, atm, cat /etc/ntp.conf restrict default nomodify notrap noquery restrict 127.0.0.1 restrict 192.168.1.0 mask 255.255.255.0 notrust nomodify notrap server ac-ntp0.net.cmu.edu iburst server ac-ntp1.net.cmu.edu iburst server ac-ntp2.net.cmu.edu iburst server clock.sjc.he.net iburst driftfile /var/lib/ntp/drift/ntp.drift logfile /var/log/ntpd/ntp.log statsdir /var/log/ntpd/ # directory for statistics files filegen peerstats file peerstats type day enable filegen loopstats file loopstats type day enable filegen clockstats file clockstats type day enable and ntp is running, ps ax | grep ntp 13012 ? S<s 0:00 /usr/sbin/ntpd -p /var/run/ntp/ntpd.pid -g -u ntp:ntp -I eth0 -i /var/lib/ntp -c /etc/ntp.conf after a few minutes, i've got time sync @ Stratum 2/3, @ Dom0, ntpq -p -c rv assID=0 status=06f4 leap_none, sync_ntp, 15 events, event_peer/strat_chg, version="ntpd 4.2....@1.1549-o Fri May 8 08:40:54 UTC 2009 (1)", processor="x86_64", system="Linux/2.6.27.29-0.1-xen", leap=00, -> stratum=2, precision=-8, rootdelay=18.717, rootdispersion=1077.662, peer=35633, refid=216.218.254.202, reftime=ce7605a0.6d9086a4 Tue, Oct 6 2009 11:06:24.427, poll=6, clock=ce7606ac.ba2a0e0c Tue, Oct 6 2009 11:10:52.727, state=2, offset=-119.499, frequency=-37.025, jitter=455.226, noise=42.407, stability=0.040, tai=0 remote refid st t when poll reach delay offset jitter ============================================================================== +AC-NTP0.net.cmu 128.237.148.140 2 u 12 64 37 99.147 -669.34 452.011 +AC-NTP1.net.cmu 128.237.148.132 2 u 13 64 37 95.951 -667.96 454.264 +AC-NTP2.net.cmu 128.237.148.132 2 u 5 64 35 89.923 -688.34 496.274 *clock.sjc.he.ne .CDMA. 1 u 15 64 37 15.566 -673.46 455.158 ntpdc -c kerninfo pll offset: -0.09179 s pll frequency: -37.025 ppm maximum error: 0.135195 s estimated error: 0.042407 s status: 0001 pll pll time constant: 6 precision: 1e-06 s frequency tolerance: 500 ppm @ DomU, ntpq -p -c rv assID=0 status=06f4 leap_none, sync_ntp, 15 events, event_peer/strat_chg, version="ntpd 4.2....@1.1549-o Fri May 8 08:40:54 UTC 2009 (1)", processor="x86_64", system="Linux/2.6.27.29-0.1-xen", leap=00, -> stratum=3, precision=-8, rootdelay=98.154, rootdispersion=357.033, peer=50391, refid=216.218.254.202, reftime=ce7605c4.85c9d4d7 Tue, Oct 6 2009 11:07:00.522, poll=6, clock=ce7606b2.b01ba2b4 Tue, Oct 6 2009 11:10:58.687, state=2, offset=-102.003, frequency=-2.249, jitter=367.417, noise=36.248, stability=0.409, tai=0 remote refid st t when poll reach delay offset jitter ============================================================================== +AC-NTP0.net.cmu 128.237.148.140 2 u 35 64 17 91.744 -557.29 359.884 +AC-NTP1.net.cmu 128.237.148.140 2 u 37 64 17 96.365 -548.70 355.430 +AC-NTP2.net.cmu 128.237.148.132 2 u 54 64 17 98.517 -509.63 363.221 *clock.sjc.he.ne .CDMA. 1 u 37 64 17 22.907 -553.69 366.781 ntpdc -c kerninfo pll offset: -0.080367 s pll frequency: -2.249 ppm maximum error: 0.12257 s estimated error: 0.036248 s status: 0001 pll pll time constant: 6 precision: 1e-06 s frequency tolerance: 500 ppm with this setup, service dovecot-custom restart Stopping dovecot done Starting dovecot ILoading modules from directory: /usr/local/lib/dovecot/imap IModule loaded: /usr/local/lib/dovecot/imap/lib01_acl_plugin.so IModule loaded: /usr/local/lib/dovecot/imap/lib10_quota_plugin.so IModule loaded: /usr/local/lib/dovecot/imap/lib11_imap_quota_plugin.so IEffective uid=65534, gid=65533, home=/tmp IQuota root: name=storage=10240 backend=maildir args= done and watching, tail -f /var/log/dovecot/*log the problem appears again, ... Oct 06 10:58:37 auth(default): Info: new auth connection: pid=17797 Oct 06 10:58:37 auth(default): Info: new auth connection: pid=17798 Oct 06 10:58:37 auth(default): Info: new auth connection: pid=17799 Oct 06 11:06:23 dovecot: Error: Time just moved backwards by 1 seconds. I'll sleep now until we're back in present. http://wiki.dovecot.org/TimeMovedBackwards and, checking syslog, ... Oct 6 11:06:22 mx ntpd[17697]: time reset -2.203456 s Oct 6 11:07:00 mx ntpd[17697]: synchronized to 128.2.1.22, stratum 2 Oct 6 11:08:11 mx ntpd[17697]: synchronized to 216.218.254.202, stratum 1 so it _looks_ like a reset was done, then stratum 2 & 1 sync were achived. as of, date Tue Oct 6 11:20:58 PDT 2009 there have been no further, related errors/entries in either dovecot logs or syslog. fixed? improved? unclear ....
