[389-users] replication failure - clock skew

[Rich Megginson]

On 02/09/2012 12:23 PM, Greg Kuchyt wrote:
> Yesterday afternoon, one of my consumers randomly crashed/rebooted. 
> Upon rebooting, its replication agreement with its master failed with 
> the following error:
>
> Unable to acquire replica: Excessive clock skew between the supplier 
> and the consumer. Replication is aborting
>
> I did a little bit of Google searching and found some list traffic 
> from a few years ago. From that I derived that this replica was hosed 
> and I would need to re-initialize it. No problem. A re-initialization 
> didn't do anything, same error. Starting from scratch from a 
> completely new/fresh replica produces the same result. That's when I 
> noticed the following errors in the logs on the master.
>
> csngen_new_csn - Warning: too much time skew (-115319 secs). Current 
> seqnum=1
>
> I downloaded the readNsState.py script attached to the following 
> ticket (https://bugzilla.redhat.com/show_bug.cgi?id=233642). Running 
> this on the master produced the following output
>
> For replica cn=replica,cn=o\3Dpotsdam.edu,cn=mapping tree,cn=config
>   len of nsstate is 40
>   CSN generator state:
>     Replica ID    : 6560
>     Sampled Time  : 1328928777
>     Time in hex   : 0x4f35d809
>     Time as str   : Fri Feb 10 21:52:57 2012
>     Local Offset  : 0
>     Remote Offset : 261
>     Seq. num      : 1
>     System time   : Thu Feb  9 14:00:01 2012
>     Diff in sec.  : -114776
>
> This leads me to believe that the clock skew problem is on the master.
>
> I am not really sure how the clock skew happened. All of these systems 
> synchronize their clocks via a centralized time server and all the 
> times on their clocks are correct. There are 3 or 4 other replicas 
> that are still receiving incremental updates fine, but any attempt to 
> add a new replica results in a failed replication agreement due to 
> excessive clock skew.
>
> I am writing to get a better understanding of the situation and see if 
> there is anything to be done to resolve this. At the moment it seems 
> as if I am caught in an unfortunate situation that will require 
> re-initialization of my master from a back-up.
>
> Thanks for any help that can be provided.
What is your 389-ds-base version and platform?
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