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<div class="moz-cite-prefix">On 10/15/2013 02:41 PM, Mark Reynolds
wrote:<br>
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<blockquote cite="mid:525DA868.6040003@redhat.com" type="cite">
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<div class="moz-text-flowed" style="font-family: -moz-fixed;
font-size: 12px;" lang="x-western"><a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="https://fedorahosted.org/389/ticket/47368">https://fedorahosted.org/389/ticket/47368</a>
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<br>
So we run into issues when trying to figure out if replicas are
in synch(if those replicas use fractional replication and "strip
mods"). What happens is that an update is made on master A, but
due to fractional replication there is no update made to any
replicas. So if you look at the ruv in the tombstone entry on
each server, it would appear they are out of synch. So using
the ruv in the db tombstone is no longer accurate when using
fractional replication. <br>
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<br>
So what we really want to know is - When there are differences when
comparing RUV max CSN values, how much of the differences are due
only to unreplicated operations?<br>
<br>
<blockquote cite="mid:525DA868.6040003@redhat.com" type="cite">
<div class="moz-text-flowed" style="font-family: -moz-fixed;
font-size: 12px;" lang="x-western"> <br>
I'm proposing a new ruv to be stored in the backend replica
entry: e.g. cn=replica,cn="dc=example,dc=com",cn=mapping
tree,cn=config. I'm calling this the "replicated ruv". So
whenever we actually send an update to a replica, this ruv will
get updated. Since we can not compare this "replicated ruv" to
the replicas tombstone ruv, we can instead compare the
"replicated ruv" to the ruv in the replica's repl
agreement(unless it is a dedicated consumer - here we might be
able to still look at the db tombstone ruv to determine the
status). <br>
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Will have to check to see if, on a dedicated consumer, the RUV is
updated by internal operations.<br>
<br>
<blockquote cite="mid:525DA868.6040003@redhat.com" type="cite">
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font-size: 12px;" lang="x-western"> <br>
Problems with this approach: <br>
<br>
- All the servers need to have the same replication
configuration(the same fractional replication policy and
attribute stripping) to give accurate results. <br>
<br>
- If one replica has an agreement that does NOT filter the
updates, but has agreements that do filter updates, then we can
not correctly determine its synchronization state with the
fractional replicas. <br>
<br>
- Performance hit from updating another ruv(in cn=config)? <br>
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Yes. We already have a lot of churn in dse.ldif due to - uuid
generator - csn generator - updating consumer RUV in each
replication agreement.<br>
<br>
<blockquote cite="mid:525DA868.6040003@redhat.com" type="cite">
<div class="moz-text-flowed" style="font-family: -moz-fixed;
font-size: 12px;" lang="x-western"> <br>
<br>
Fractional replication simply breaks our monitoring process.
I'm not sure, not without updating the repl protocol, that we
can cover all deployment scenarios(mixed fractional repl agmts,
etc). However, I "think" this approach would work for most
deployments(compared to none at the moment). For IPA, since
they don't use consumers, this approach would work for them.
And finally, all of this would have to be handled by a updated
version of repl-monitor.pl. <br>
<br>
This is just my preliminary idea on how to handle this.
Feedback is welcome!! <br>
<br>
Thanks in advance, <br>
Mark <br>
<div class="moz-txt-sig"> <br>
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<pre class="moz-signature" cols="72">--
Mark Reynolds
389 Development Team
Red Hat, Inc
<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:mreynolds@redhat.com">mreynolds@redhat.com</a></pre>
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