Message-ID: <519CF8CC.1030204@optionshouse.com>
Date: Wed, 22 May 2013 11:56:44 -0500
From: Shaun Thomas <sthomas@optionshouse.com>
Reply-To: <sthomas@optionshouse.com>
Organization: Peak6
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
	rv:17.0) Gecko/20130510 Thunderbird/17.0.6
MIME-Version: 1.0
To: Merlin Moncure <mmoncure@gmail.com>
CC: Greg Smith <greg@2ndquadrant.com>, Tomas Vondra <tv@fuzzy.cz>,
	<pgsql-performance@postgresql.org>
Subject: Re: Reliability with RAID 10 SSD and Streaming Replication
References: 
 <CAAE-9WHMycEZOB5J6HKME5AZLEdL2hYF+FV8hzbLksJinq=EJg@mail.gmail.com>
	<51957499.6050905@fuzzy.cz> <519991EB.8010208@2ndQuadrant.com>
	<519A8E29.60702@fuzzy.cz>
	<CAHyXU0wvW-USgbkXAYEHLG2fHgj=UdZi1aCFoVWBMQEsOFZy+A@mail.gmail.com>
	<519C0EFD.9080002@2ndQuadrant.com>
	<CAHyXU0ymFT7Sqw77yPryGWKEpjV4Wv9Vkc21vGtPKo0GZWGg8A@mail.gmail.com>
In-Reply-To: 
 <CAHyXU0ymFT7Sqw77yPryGWKEpjV4Wv9Vkc21vGtPKo0GZWGg8A@mail.gmail.com>
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
content-transfer-encoding: 7bit
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

On 05/22/2013 08:30 AM, Merlin Moncure wrote:

> I'm not claiming to work with extremely high transaction rate systems
> but then again neither are most of the people reading this list.
> Disk drives are obsolete for database installations.

Well, you may not be able to make that claim, but I can. While we don't 
use Intel SSDs, our first-gen FusinoIO cards can deliver about 20k 
PostgreSQL TPS of our real-world data right off the device before 
caching effects start boosting the numbers. These days, devices like 
this make our current batch look like rusty old hulks in comparison, so 
the gap is just widening. Hard drives stand no chance at all.

An 8-drive 15k RPM RAID-10 gave us about 1800 TPS back when we switched 
to FusionIO about two years ago. So, while Intel drives themselves may 
not be able to hit sustained 100x speeds over spindles, it's pretty 
clear that that's a firmware or implementation limitation.

The main "issue" is that the sustained sequence scan speeds are 
generally less than an order of magnitude faster than drives. So as soon 
as you hit something that isn't limited by random IOPS, spindles get a 
chance to catch up. But those situations are few and far between in a 
heavy transactional setting. Having used NVRAM/SSDs, I could never go 
back so long as the budget allows us to procure them.

A data warehouse? Maybe spindles still have a place there. Heavy 
transactional system? Not a chance.

-- 
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
312-676-8870
sthomas@optionshouse.com

______________________________________________

See http://www.peak6.com/email_disclaimer/ for terms and conditions related to this email


-- 
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance