[time-nuts] Absolutely unbelievable

Tom Clifton kc0vsj at yahoo.com
Tue May 21 09:57:56 EDT 2013

Never guess how long ago I purchased a pair of these things...   I thought that everybody would have figured this out by now and would be using a 2.6 kernel
FSB #:098-50620-059 Date: August 3rd, 2012
System: SyncServer S2xx Series Network Time Servers

Product Identity: NTP Servers
NOTE: Find a copy of this FSB in Support section of our website at http://www.symmetricom.com/.
Behavior: Affects all S200 | S250 | S250i SyncServer Series Units
For a SyncServer S2xx Series SyncServer that remains running continuously for 497 days, it will likely
reboot on day 497 or possibly the unit’s display or key pad may become nonfunctional on that day.
The issue is in relation to the Linux 2.4 kernel being used inside the S2xx Series SyncServer. This known
Linux issue can cause unexpected behavior of the SyncServer S2xx Series when uptime reaches 497
The 2.4 kernel computes the system uptime based on the internal jiffies counter, which counts the time
since boot in units of 10 milliseconds (100 Hz), or jiffies. This counter is a 32-bit counter, which has a
maximum value of 2^32, or 4,294,967,296. When the counter reaches this value (after 497 days, 2
hours, 27 minutes, and 53 seconds, or approximately 16 months), it wraps back around to zero and
continues to increment. When the jiffies counter wraps, unexpected side effects described above in the
Behaviors section may be observed

Recommended Actions:
Symmetricom recommends restarting the S2xx SyncServer Series Server at least once every year as part
of a scheduled administrative maintenance program.
Contact Information:
Symmetricom Inc Toll Free Calls
2300 Orchard Parkway 888.367.7966 option 1, then option 2
San Jose, CA 95131
Toll Calls
408-428-7907 (1) (

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