Running Dovecot 2.0.8 on 32bit Centos5.5. The machine is a VMWare ESX VM. I'm seeing a lot of warning messages in syslog as follows: 2011-01-14T11:45:37.315917+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds 2011-01-14T11:46:00.598006+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds 2011-01-14T11:46:25.364405+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds 2011-01-14T11:46:27.030658+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds 2011-01-14T11:46:49.712202+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds 2011-01-14T11:48:07.600748+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds 2011-01-14T11:48:23.195587+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds 2011-01-14T11:48:37.342804+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds 2011-01-14T11:48:42.671037+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds 2011-01-14T11:48:45.903081+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds 2011-01-14T11:48:49.001119+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds 2011-01-14T11:48:58.935835+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds 2011-01-14T11:49:15.046253+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 104 seconds 2011-01-14T11:49:16.842962+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds I've checked the clock settings in Centos and it all looks OK. NTP is running and not complaining about clock drift. Vmware recommend appending 'divider=10 clocksource=acpi_pm' kernel boot options to prevent timekeeping issues, which I've done. Has anyone else encountered this message? Is it something to be concerned about? Thanks, Ian.
On 01/13/2011 09:01 PM, Ian B wrote:> Running Dovecot 2.0.8 on 32bit Centos5.5. The machine is a VMWare ESX VM. > > I'm seeing a lot of warning messages in syslog as follows: > > 2011-01-14T11:45:37.315917+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds > 2011-01-14T11:46:00.598006+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > 2011-01-14T11:46:25.364405+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds > 2011-01-14T11:46:27.030658+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > 2011-01-14T11:46:49.712202+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > 2011-01-14T11:48:07.600748+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > 2011-01-14T11:48:23.195587+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > 2011-01-14T11:48:37.342804+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > 2011-01-14T11:48:42.671037+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > 2011-01-14T11:48:45.903081+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds > 2011-01-14T11:48:49.001119+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds > 2011-01-14T11:48:58.935835+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 105 seconds > 2011-01-14T11:49:15.046253+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 104 seconds > 2011-01-14T11:49:16.842962+08:00 imap4 dovecot: imap: Warning: Time jumped forwards 106 seconds > > I've checked the clock settings in Centos and it all looks OK. NTP is running and not complaining about clock drift. Vmware recommend appending 'divider=10 clocksource=acpi_pm' kernel boot options to prevent timekeeping issues, which I've done. > > Has anyone else encountered this message? Is it something to be concerned about? > > Thanks, > Ian. >See http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1006427&sliceId=1&docTypeID=DT_KB_1_1&dialogID=23956052&stateId=1%200%2023952415 In particular, see NTP Recommendations and VMware Tools bits at the bottom. -- -Eric 'shubes'
On Fri Jan 14 07:23:32 EET 2011, Eric Shubert wrote:>See >http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1006427&sliceId=1&docTypeID=DT_KB_1_1&dialogID=23956052&stateId=1%200%2023952415 > > >In particular, see NTP Recommendations and VMware Tools bits at the bottom.Thanks, I've read through that document a couple of times now & I'm fairly sure my system 'ticks all the boxes' yet the warning messages continues. I can see no noticeable time discrepancy when I do periodic time checks from the command line comparing against another system's clock - certainly not 2 minute error margin Could this be a time mismatch between imap client & server? Ian.
--- On Fri, 14/1/11, Tom Hendrikx <tom at whyscream.net> wrote:> > I had this problem too when I setup a VMware guest last > month (noticed > through strange spikes in munin's ntp monitoring, not > through dovecot > logs). After some research I found out that I had VMware > time > synchronisation (host to guest) enabled, and NTP in the > guest running. > The ESX host clock was some 90+ seconds behind, so VMware > stalled my > clock once in a while, after which NTP corrected it again. > > I asked the ESX admin to fix the clock, but disabled the > VMware > synchronisation and now use only ntp in the guest. Never > looked back. > > So in stead of 'ticking all the boxes', explain your setup. > You have NTP > enabled, but what does VMware do?Thanks for the post. I've checked my setup - the guest is not set to sync with the VMware host. NTP is running with local clock server commented out & 'tinker panic 0' set. It sounds like this is not a Dovecot issue so I'll stop posting to this list now and seek help elsewhere. What negative effects to Dovecot would I expect to see where the system clock is constantly changing?