[Dovecot] "Time just moved backwards" in Dovecot in a Xen DomU
PGNet Dev
pgnet.dev+dovecot at gmail.com
Tue Oct 6 21:23:08 EEST 2009
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 4.2.4p6 at 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 4.2.4p6 at 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 ....
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