On 10/20/2011 12:45 AM, Das, Jyoti Ranjan (STSD) wrote:
Hi,
I am new to 389 directory server. Could you please help me in the
below mentioned query?
Thank you very much in advance.
Problem statement:
Data loss during the replication between Supplier and consumer when
master changelog db file is being deleted due to some reason ,
consumer is imported with some stale data and consumer doesn't want
initialization during the new replication agreement. The test scenario
is given below.
Test scenario:
Steps:
1)Topology
Supplier -----------Replication agreement-----------------> Hub
Both replicas are in sync at this time as mentioned below.
Let's take this sample example: Five entries has been added starting
from CSN1 to CSN5
2)Take a db2ldif with "-r" option from the Hub replica.
3)Add another 5 entries in the supplier. Let's take their CSN numbers
are starting from CSN6 to CSN10
4)Delete the replication agreements
Before or after CSN6 to CSN10 have been replicated to the Hub?
5)Delete the master changelog db file from the changelogdb directory.
Supplier or Hub?
6)Add another 5 entries in the supplier. Let's take their CSN numbers
are staring from CSN11 to CSN15
7)Import the ldif file taken in Step-2 in the Hub replica( it's a
initialization of consumer with the stale data)
8)Create the replication agreement between master and hub with the "do
not initialize" option.
9)Now we will see the data loss starting from CSN6 to CSN14. Only
entry with CSN15 will be replicated to the consumer and also will
continue further with successful replication
Questions:
*/1)/**/Is this a correct approach in this scenario to continue with
replication even if there are data losses instead of halting the
replication? /*
From the code analysis:
File: " ldapserver/ldap/servers/plugins/replication/cl5_api.c"
If the requested CSN number is now found in the changelog db file and
also not there in the purge list, it makes the following assumption
and continues with replication
/* there is a special case which can occur just after migration - in
this case,
the consumer RUV will contain the last state of the supplier before
migration,
but the supplier will have an empty changelog, or the supplier
changelog will
not contain any entries within the consumer min and max CSN - also,
since
the purge RUV contains no CSNs, the changelog has never been purged
ASSUMPTIONS - it is assumed that the supplier had no pending changes
to send
to any consumers; that is, we can assume that no changes were lost
due to
either changelog purging or database reload - bug# 603061 -
ri...@netscape.com */
*/ Is it a correct approach in this scenario to halt
the replication with a fatal error message in the error log file?/*
Probably, but then this code would have to be a lot smarter to figure
out that the problem is due to stale data being imported into the
consumer. Please file a bug with exact steps to reproduce this problem.
*//*
Regards,
Jyoti
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