Re: Amazon High I/O instances

Ok, make sense .. I will update that as well and report back. Thank you for
your advice.

Sébastien

On Wed, Sep 12, 2012 at 8:04 PM, John R Pierce <pierce(at)hogranch(dot)com> wrote:

> On 09/12/12 4:49 PM, Sébastien Lorion wrote:
>
>> You set shared_buffers way below what is suggested in Greg Smith book
>> (25% or more of RAM) .. what is the rationale behind that rule of thumb ?
>> Other values are more or less what I set, though I could lower the
>> effective_cache_size and vfs.zfs.arc_max and see how it goes.
>>
>
> I think those 25% rules were typically created when ram was no more than
> 4-8GB.
>
> for our highly transactional workload, at least, too large of a
> shared_buffers seems to slow us down, perhaps due to higher overhead of
> managing that many 8k buffers. I've heard other read-mostly workloads,
> such as data warehousing, can take advantage of larger buffer counts.
>
>
>
>
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> john r pierce N 37, W 122
> santa cruz ca mid-left coast
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