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Transactional Replication Performance Issues After Migration From 2000 to 2008


Transactional Replication Performance Issues After Migration From 2000 to 2008

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chris.roddis-ferrari
chris.roddis-ferrari
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We currently have 140 SQL 2000 publications replicating to a single 2008 server with about 25 articles. 5 of the articles are quite substantial. We are in the process of migrating to new 2008 servers that perform in general significantly better than the old 2000 infrastructure. Previously all replication ran fine with a latency of no more than a minute at any time even under peak load. We have migrated about 60 servers to the new 2008 infrastructure but the latency has now shot up. This makes no sense in terms of performance. We have tried a number of things to resolve this but have so far been unsuccessful. The 2008 and 2000 publications are both going to the same DB and using the same replication procs.

First the @status in add article needed changing from the original script where it was 0 to 24. This gave a significant improvement but the latency is still up to 40 minutes at peak times.
We have tried changing from push to pull. This made the performance worse.
We have changed the PollingInterval on the distribution agent from 5 (2008 default) to 10 (2000 default). This made no noticeable difference.
We have changed the ImmediateSync setting to 0 from 1. This made no noticeable difference.
We have ensured the index etc is ok on the central MSreplication_unscriptions table. This made no noticeable difference.
We have tried lock hints on some of the replication procs. This made no noticeable difference.

Any ideas would be much appreciated
chris.roddis-ferrari
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For reference all changes except the @Status and PollingInterval have been made at 2 or 3 of the 60 new servers to test, not at all 60.
MysteryJimbo
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Have you established where the latency is?

Log reader to distribution server?
Distribution agent to subscriber?
chris.roddis-ferrari
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Cheers for the response. The publisher is its own distributor, there isn't a separate server for this. I will post some outputs from the Distribution and Log Reader agents shortly
MysteryJimbo
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Also, is the latency across all subscribers?
chris.roddis-ferrari
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Some are worse than others, but there is latency across all the new servers. There was a correlation to the number of records in msrepl_commans and performance. But even when we set ImmediateSync to 0 and running the Distribution Cleanup job every 30 mins to keep the table size, this didn't help with I guess suggests it is an issue with applying the commands at the subscriber rather than getting the off the distributor?

There is no latency on the 2000 boxes
MysteryJimbo
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chris.roddis-ferrari (11/14/2013)
Some are worse than others, but there is latency across all the new servers. There was a correlation to the number of records in msrepl_commans and performance. But even when we set ImmediateSync to 0 and running the Distribution Cleanup job every 30 mins to keep the table size, this didn't help with I guess suggests it is an issue with applying the commands at the subscriber rather than getting the off the distributor?

There is no latency on the 2000 boxes


It could be.

For clarity, you have 200 publishers (140/60 2000/2008) delivering to a single subscriber using push transactional replication. All of the 60 2008 publishers are experiencing latency at a currently unknown "bottleneck".

Are the subscriptions going to the same database/objects?
chris.roddis-ferrari
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Yes all going to the same database/objects. The split is 80 on 2000 and 60 on 2008

Cheers
Bhuvnesh
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Any Drive(disk) level changes happened ? like comparatively low graded disk is being used now.

-------Bhuvnesh----------
I work only to learn Sql Server...though my company pays me for getting their stuff done;-)
chris.roddis-ferrari
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Disk is now significantly better
Was previously 2 Utlra SCSI 420 72GB drives RAID1-0 and is now 4 SAS 300GB drives 2 RAID1-0 pairs.
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