FreeLists / oracle-l / Re: Big RAC Benchmark Performance Tips?

[Mogens Nørrgaard <mln@xxxxxxxxxxxx>]

Re 1: No. Cache Fusion is no longer an issue. It's free.
Re 1: Yes. Cache Fusion is of course still a cost. It's neccessary, 
therefor it is, and therfor it has a cost. You can call it anything you 
like (and people do), but data partitioning still, after all these 
years, minimize pinging.

Re 2: No idea. I suspect it doesn't matter one iota whatsoever. It's 
just "I've heard this" vs "I've heard that".

Re 3: Why would you want to disable the excellent index skip scan? Good 
luck with AUM and ASSM. This test can't fail, as long as you're using 
anything Oracle recommends.

Re 4: Forget best practices. Forget silver bullets. They work for one 
site, but never for another. There are only worst practices.

Good luck.

Mogens

VIVEK_SHARMA wrote:

> Folks
>
> A 4-node RAC BIG benchmark with Oracle 10g / AIX 5.3L using a Hybrid 
> Banking App. is underway.
>
> *Qs1 Does Cache fusion(Traffic between the nodes thru the 
> interconnects) continue to be an expensive operation in Oracle 10g?*
>
> To minimize Cache fusion, Manually Transactions have been grouped such 
> that transactions accessing different DB Server Nodes access different 
> respective Table partitions (& NOT the same Table partition). Thus 
> Different Object BLOCKS are accessed in different DB Server nodes.
>
> NOTE – Partitioning of heavier underlying tables has been done such 
> that different partitions lie in DIFFERENT Tablespaces (& hence 
> datafiles).
>
> *Qs2 Is Low Latency Protocol - LLT protocol (of Veritas) equivalent or 
> something similar available with GPFS?*
>
> Currently default (UDP) is being used.
>
> NOTE - A Past benchmark done by us on SUN using VXFS (Veritas) with 
> both Low Latency Protocol (LLT) & User Datagram Protocol (UDP, 
> Default) showed LLT had a *98% Lower interconnect utilization* versus UDP.
>
> *Qs3* Any additional init.ora parameters for performance apart from 
> the following which have been set?
>
> db_writer_processes=16
>
> db_cache_advice=OFF
>
> event='10196 trace name context forever, level 10' (to disable index 
> skip scan)
>
> _library_cache_advice = FALSE
>
> _log_simultaneous_copies 256
>
> _b_tree_bitmap_plans = FALSE (as NO Bitmap indexes exist)
>
> _check_block_after_checksum TRUE
>
> _system_trig_enabled FALSE (Benchmark Has NO need for Triggers)
>
> _wait_for_sync TRUE
>
> NOTE - Standard features i.e. AUM, Tempfiles & ASSM are being used.
>
> *Qs4 Other best practices to deploy?*
>
> Will provide Statspack, Other diagnostics info. as needed.
>
> Thanks indeed
>
> *Configuration*:-
>
> APP & DB machines – *P5* series
>
> Application Hybrid – (OLTP + Batch nature of Trans).
>
> Oracle 10.2
>
> AIX 5.3
>
> Filesystem GPFS
>
> Storage Box DS8300
>
> Hardware RAID 1+0
>
> Underlying Hardware Stripe Unit Size 64 KB
>
> Overlying Logical Volume Manager Stripe Unit Size 32 MB (S.A.M.E.)
>
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