Re: shareplex replication speed up

  • From: zhu chao <zhuchao@xxxxxxxxx>
  • To: Bruce McCartney <bruce.mccartney@xxxxxxxxxxxxxxxxx>
  • Date: Tue, 15 Nov 2005 22:04:12 +0800

Thanks for your sharing. We did stripe the volume using hardware. IO
on queue filesystem is actually excellent , less than 3ms for average
read/write.

Seems we reached some kind of bottlenecks. I noticed each
insert/delete statement caused average 3 disk IO/30 logical io(due to
a lot of indexes to update), and each Disk read is around 8ms. Taking
account into the other overhead like Logical accesss etc, each
insert/delete takes around 24ms. So one second we can do around 50 DML
on that table. Around 100 on two core tables.

The capture process is fine. Post queue delays. One dirty tip is to
set to unsafe mode, but we can't always rely on such solution.

We can talk more about using splex experience offline.

By the way, index leaf node split is not much. I checked it in statspack.
Thank you
On 11/14/05, Bruce McCartney <bruce.mccartney@xxxxxxxxxxxxxxxxx> wrote:
> Zhu,
> We had similar issues with shareplex and were able to scale to much higher 
> numbers by most of what you sugested.  We also found that the filesystem I/O 
> on the shareplex queue files were a bottleneck. Using hardware sriping there 
> really helped - especially if they got large as the I/O routines of shareplex 
> seemed to worsen the deeper the queue (i believe this has since been resolved 
> - but you are on old software).
> The other thing to look at is row migration (expansion of a row causing it to 
> relocate).  This operation causes additional overhead for the capture process 
> mostly so may not apply if capture is keeping up but posting is lagging...
>
> Hope that helps
>
> Bruce McCartney
> 403.615.3350
>
>
> -----Original Message-----
>    From: "zhu chao"<zhuchao@xxxxxxxxx>
>    Sent: 11/14/05 8:22:15 AM
>    To: "Oracle-L"<oracle-l@xxxxxxxxxxxxx>
>    Subject: shareplex replication speed up
>
>    hi, all,
>        We are using shareplex to replicate transaction data. We are still
>    using old oracle 8174 and shareplex 3.1.4.
>        We consistently see shareplex unable to keep up with primary
>    database so we have to slow down every batch job. We are only able to
>    do less than 120 transactions per second. Most transactions happen on
>    two core tables and there are a lot of indexes in these two tables.
>       Box is running on a 12 CPU box and with tons of memory. SAN
>    performance is ok (less than 10ms for read and 5 ms for write).
>       Currently we tried:
>    --increase sga as big as possible.
>    --rebuild index on the table to reduce index size to make it keep in
>    data buffer.
>    --set keep buffer pool for core tables.
>    -- we used quick IO for oracle redo log files..
>    -- we setup multiple post queue to make parallel post.
>    --the post queue process oracle sessions is mainly waiting on db file
>    sequential read.
>
>      Any other ideas to make shareplex replicate faster?
>
>     Regards
>    Zhu Chao
>    www.cnoug.org
>    --
>    //www.freelists.org/webpage/oracle-l
>
>
>
>
>
>


--
Regards
Zhu Chao
www.cnoug.org
--
//www.freelists.org/webpage/oracle-l


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