From: Gerardo Herzig <gherzig@fmed.uba.ar>
To: Pietro Pugni <pietro.pugni@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL
Date: Wed, 1 Apr 2015 23:19:38 -0300 (ART)
Message-ID: <87131335.225702.1427941178942.JavaMail.root@fmed.uba.ar> (raw)
In-Reply-To: <732B95A3-FEC8-4623-9AC5-98FD30F00863@gmail.com>
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Ok, a quick view on the system, and some things that may be important to note:
> Our deployment machine is a Dell PowerEdge T420 with a Perc H710 RAID
> controller configured in this way:
>
> * VD0: two 15k SAS disks (ext4, OS partition, WAL partition,
> RAID1)
> * VD1: ten 10k SAS disks (XFS, Postgres data partition, RAID5)
>
Well...usually RAID5 have the worst performance in writing...EVER!!! Have you tested this in another raid configuration? RAID10 is usually the best bet.
>
>
> This system has the following configuration:
>
> * Ubuntu 14.04.2 LTS (GNU/Linux 3.13.0-48-generic x86_64)
> * 128GB RAM (DDR3, 8x16GB @1600Mhz)
> * two Intel Xeon E5-2640 v2 @2Ghz
> * Dell Perc H710 with 512MB RAM (Write cache: "WriteBack", Read
> cache: "ReadAhead", Disk cache: "disabled"):
> * VD0 (OS and WAL partition): two 15k SAS disks (ext4, RAID1)
> * VD1 (Postgres data partition): ten 10k SAS disks (XFS,
> RAID5)
> * PostgreSQL 9.4 (updated to the latest available version)
> * moved pg_stat_tmp to RAM disk
>
>
[...]> versions.
>
You did not mention any "postgres" configuration at all. If you let the default checkpoint_segments=3, that would be an IO hell for your disk controler...and the RAID5 making things worst...Can you show us the values of:
checkpoint_segments
shared_buffers
work_mem
maintenance_work_mem
effective_io_concurrency
I would start from there, few changes, and check again. I would change the RAID first of all things, and try those tests again.
Cheers.
Gerardo
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To: pgsql-performance@postgresql.org
Cc: gherzig@fmed.uba.ar, pietro.pugni@gmail.com
Subject: Re: Can't get Dell PE T420 (Perc H710) perform better than a MacMini with PostgreSQL
In-Reply-To: <87131335.225702.1427941178942.JavaMail.root@fmed.uba.ar>
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