From: Greg Smith <greg@2ndquadrant.com>
To: Anj Adu <fotographs@gmail.com>
Cc: pgsql-admin@postgresql.org
Subject: Re: more 10K disks or less 15K disks
Date: Wed, 28 Apr 2010 21:12:10 -0400
Message-ID: <4BD8DCEA.2020003@2ndquadrant.com> (raw)
In-Reply-To: <i2pf2fd819a1004281127sf91d988cua1d95d13d09dae09@mail.gmail.com>
References: <i2pf2fd819a1004281127sf91d988cua1d95d13d09dae09@mail.gmail.com>
Anj Adu wrote:
> I am faced with a hardware choice for a postgres data warehouse
> (extremely high volume inserts..over 200 million records a day)
That's an average of 2314 per second, which certainly isn't easy to pull
off. You suggested you're already running this app. Do you have any
idea how high the volume of data going to the WAL is relative to
everything else?
> 12 x 600G disks (15K) (the new Dell Poweredge C server)
> or
> 24 x 600G (10K disks)
>
You can expect the 15K disks to be 30% (more sequential work) to 50%
(random/commit work) faster than a similar 10K drive. So from most
perspectives, twice as many 10K drives should be considerably faster.
The main point of concern here is the commit rate, which you can't
necessarily improve just by throwing drives at it. That's based on how
fast the drives spin, so there's the potential to discover a 50%
regression there compared to the setup you have right now. With the
RAID card in there, it should be fine, but it's something to be
concerned about.
Also, you didn't mentioned the RAID card for the new system, and whether
it would be the same in both setups or not. That can be as important as
the drives when you have larger arrays. The LSI Megaraid card Dell is
using for the Perc6i is quite fast, and you'll need to make sure you get
something just as good for the new server.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com www.2ndQuadrant.us
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-admin@postgresql.org
Cc: greg@2ndquadrant.com, fotographs@gmail.com
Subject: Re: more 10K disks or less 15K disks
In-Reply-To: <4BD8DCEA.2020003@2ndquadrant.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox