Re: "gc current block busy" wait in Concurrent BATCH Processes Run

gc means global cache, which means it's cache fusion/interconnect related.

More than likely you have processes on both/all nodes of the cluster writing to the same table(s) and cache fusion is having trouble keeping up with the communication of which blocks are dirty (and sending the data back and forth) and which are not.

In my experience with RAC, if you have a lot of writes to a set of tables you're much better off localizing all those connections on one node so you don't have the "gc" wait events. Throughput goes up as well.

Not exactly what Oracle is marketing when they talk about RAC, but that has been my experience.

Finn

On 2/13/08, VIVEK_SHARMA <VIVEK_SHARMA_at_infosys.com> wrote:
>
>
> Folks
>
> In a Benchmark Run, 256 concurrent BATCH Processes on RAC using Dedicated
> Sessions (NON-MTS) showing the following Waits:-
>
> How is the "gc current block busy" wait to be addressed?
> From the Statspack Report (Level 7) which section gives the Objects which
> is incurring this wait? Is it the "Segments By Current Blocks Received"
> section OR the "Segments by CR Blocks Received" section?
>
> Will share the Statspack Report, as needed.
>
> Config:-
> Oracle 10.2.0.3 on 3 Node RAC
> Solaris 10
>
> Cheers
>
> Vivek
>
> Statspack Report's Time Elapsed: 11.97 (mins)
>
>
>
> Top 5 Timed Events
> Avg %Total
>
> ~~~~~~~~~~~~~~~~~~
> wait Call
>
> Event Waits Time
> (s) (ms) Time
>
> ----------------------------------------- ------------ ----------- ------
> ------
>
> CPU time 5,854
> 57.6
>
> gc current block busy 24,910 1,463 59
> 14.4
>
> SQL*Net break/reset to client 1,075,218 1,285 1
> 12.6
>
> gcs log flush sync 103,520 511
> 5 5.0
>
> gc buffer busy 6,489
> 367 57 3.6
>
> -------------------------------------------------------------
>
>
>
> Host CPU (CPUs: 120)
>
> ~~~~~~~~ Load Average
>
> Begin End User System Idle WIO WCPU
>
> ------- ------- ------- ------- ------- ------- --------
>
> 8.58 9.54
>
> 8.26 15.61 76.13 0.00 1.19
>
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