Re: Golden Gate - cachemgr settings

Hi

I set it to 4G - 8G. The default value is way too much, a few years ago it caused server swapping and node evictions in one of RAC installations because huge transactions (50 million rows update transaction) are cached in memory which is way too much.

Thanks

On Wed, Feb 14, 2018 at 11:20 AM, Niall Litchfield < niall.litchfield_at_gmail.com> wrote:

> Hi all
>
> We're in the process of implementing Golden Gate. We've observed that by
> default on 64bit systems Golden Gate wants 64GB of memory for cache. From
> https://docs.oracle.com/goldengate/1212/gg-winux/
> GWURF/gg_parameters017.htm#GWURF413 " Sets a soft limit for the amount of
> virtual memory (cache size) that is available for caching transaction data.
> On 64-bit systems, the default is 64 GB "
>
> Reserving 64G of ram for Golden Gate seems an extraordinarily large
> amount, especially on a system where multiple GG processes might be
> running. Similarly allowing this memory to swap out seems to rather negate
> the purpose of a cache :). There's a repeated warning in the docs *not to
> control this* without contacting Oracle Support for guidance. Our
> engagement with Oracle Support hasn't exactly been stellar - they're happy
> to look at individual cases, but general guidance isn't really in their
> remit.
>
> So, for folks out there using GG, do you set the CACHESIZE parameter to
> control GG memory usage, if so how? Is it really on a case by case basis.
> If not do you observe GG really using 64g ram for cache?
>
> --
> Niall Litchfield
> Oracle DBA
> http://www.orawin.info
>

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