Re: Tuning the configuration

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From: pgsql-performance-owner(at)postgresql(dot)org <pgsql-performance-owner(at)postgresql(dot)org> on behalf of Evgeniy Shishkin <itparanoia(at)gmail(dot)com>
Sent: Thursday, December 11, 2014 7:11 AM
To: Andrea Suisani
Cc: mfatticcioni(at)mbigroup(dot)it; pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] Tuning the configuration

> On 11 Dec 2014, at 15:02, Andrea Suisani <sickpig(at)opinioni(dot)net> wrote:
>
> On 12/10/2014 11:44 AM, Maila Fatticcioni wrote:
>> 2- I would like to use the two SDD to store the wal file. Do you think
>> it is useful or how should I use them?
>
> I definitely would give it a try.
>

> I don't understand the logic behind using drives,
> which are best for random io, for sequent io workloads.

> Better use 10k sas with BBU raid for wal, money wise.

Very much agree with this. Because SSD is fast doesn't make it suited for certain things, and a streaming sequential 100% write workload is one of them. I've worked with everything from local disk to high-end SAN and even at the high end we've always put any DB logs on spinning disk. RAID1 is generally sufficient. SSD is king for read heavy random I/O workload.

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