- 11 minute mode is not keeping the hardware clock in sync with the system clock
Automatic Hardware Clock Synchronization By the Kernel You should be aware of another way that the Hardware Clock is kept syn- chronized in some systems. The Linux kernel has a mode wherein it copies the System Time to the Hardware Clock every 11 minutes. This is a good mode to use when you are using something sophisticated like ntp to keep your System Time synchronized. (ntp is a way to keep your Sys- tem Time synchronized either to a time server somewhere on the network or to a radio clock hooked up to your system. See RFC 1305). This mode (we’ll call it "11 minute mode") is off until something turns it on. The ntp daemon xntpd is one thing that turns it on. You can turn it off by running anything, including hwclock --hctosys, that sets the System Time the old fashioned way. To see if it is on or off, use the command adjtimex --print and look at the value of "status". If the "64" bit of this number (expressed in binary) equal to 0, 11 minute mode is on. Otherwise, it is off. If your system runs with 11 minute mode on, don’t use hwclock --adjust or hwclock --hctosys. You’ll just make a mess. It is acceptable to use a hwclock --hctosys at startup time to get a reasonable System Time until your system is able to set the System Time from the external source and start 11 minute mode.
We experienced an issue with application software and saw this in the log.
set_rtc_mmss: can't update from 56 to 8
- Red Hat Enterprise Linux 5
- Red Hat Enterprise Linux 6
Subscriber exclusive content
A Red Hat subscription provides unlimited access to our knowledgebase of over 48,000 articles and solutions.