Re: Tuning the configuration

On 12/10/2014 11:44 AM, Maila Fatticcioni wrote:
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> Hello.
> I need to tune a postgres installation I've just made to get a better
> performance. I use two identical servers with a hot replication
> configuration. The two servers have the following hardware:
>
> Dual Processor Intel Xeon E5-2640V2 20Mb cache 2.00Ghz,
> Ram Mem. 32Gb DDR-3 Ecc Registered,
> Controller MegaRaid 8-ports 1Gb cache,
> 4 Enterprise Hdd NL Sas 600 4Tb Sata,
> 2 Samsung SSD 840 Pro Series 512Gb,
> 2 Hdd 500 Gb
>
> I made a software raid with the last two hard disks with ext4 and I
> installed Ubuntu 14.04.1 LTS (I have to use this SO) on it. I made a
> hardware raid with the four SAS hard disks and I mount the partition
> on it with ext4 without journaling and I put the database on it.

Leaving aside all the valid points Patrick already made, as of late I've found
xfs a better choice for Postgres, performance wise.

> Now I have two more steps to do.
>
> 1- could you please help tuning the configuration? What are the best
> value I should use for wal_buffers and shared_buffers?

it's probably outdated but you could try to read Greg Smith's
"PostgreSQL 9.0 High Performance", because at least you
could have an idea of almost all the attack-points you
could use to increase you overall performance.

Even in the archive of this very mailinglist you'll surely find
a lot of good advice, e.g. one that I've read here recently is
avoid using any kernels between ver 3.0 and 3.8
(http://www.databasesoup.com/2014/09/why-you-need-to-avoid-linux-kernel-32.html)

> 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.

Andrea