Re: Amazon High I/O instances

Is dedicating 2 drives for WAL too much ? Since my whole raid is comprised
of SSD drives, should I just put it in the main pool ?

Sébastien

On Wed, Sep 12, 2012 at 8:28 PM, Sébastien Lorion
<sl(at)thestrangefactory(dot)com>wrote:

> 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.
>>
>>
>>
>>
>> --
>> john r pierce N 37, W 122
>> santa cruz ca mid-left coast
>>
>>
>>
>>
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>
>