we've had the same experience here - with older SATA 2 (3Gbps) - in spite
of SSD having no spin latency, the bus speed itself was half of the SAS-2
(6Gbps) we were using at the time which negated SSD perf in this area. HDD
was about the same perf as SSD for us.


On Mon, Jan 15, 2018 at 1:32 PM, Georg H. <geor...@silentrunner.de> wrote:

> Hello Neto
> Am 14.01.2018 um 21:44 schrieb Neto pr:
>> Dear all
>> Someone help me analyze the two execution plans below (Explain ANALYZE
>> used), is the  query 9 of TPC-H benchmark [1].
>> I'm using a server HP Intel Xeon 2.8GHz/4-core - Memory 8GB HDD SAS 320GB
>> 15 Krpm AND SSD Sansung EVO 500GB.
>> My DBMS parameters presents in postgresql.conf is default, but in SSD I
>> have changed random_page_cost = 1.0.
>> you are comparing a SAS Drive against a SATA SSD. Their interfaces serve
> a completely different bandwidth.
> While a SAS-3 device does 12 Gbit/s  SATA-3 device  is only able to
> transfer 6 Gbit/s  (a current SAS-4 reaches 22.5 Gbit/s)
> Do a short research on SAS vs SATA and then use a SAS SSD for comparison :)
> regards
> Georg

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