Message-ID: <51999410.2020600@2ndQuadrant.com>
Date: Sun, 19 May 2013 23:10:08 -0400
From: Greg Smith <greg@2ndQuadrant.com>
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7;
	rv:14.0) Gecko/20120713 Thunderbird/14.0
MIME-Version: 1.0
To: Cuong Hoang <climbingrose@gmail.com>
CC: Jeff Janes <jeff.janes@gmail.com>, Merlin Moncure <mmoncure@gmail.com>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Reliability with RAID 10 SSD and Streaming Replication
References: 
 <CAAE-9WHMycEZOB5J6HKME5AZLEdL2hYF+FV8hzbLksJinq=EJg@mail.gmail.com>
	<CAMkU=1xKCdJ0hdBqu66z2Fhf-WELoNZ+CZYKdD3wHCdO49yZ+A@mail.gmail.com>
	<CAHyXU0xE83Fg=gS80Aw+MzZP8_XnLWXytsfLVwe9RGRJb4OJ5w@mail.gmail.com>
	<CAMkU=1x6dE-seD8o0V0GvGg6q+cpU_C1AXfMVYHtyTg=LJcw=A@mail.gmail.com>
	<CAAE-9WFa+3qv3V9zE0kyWuhdbPjNEJPW8F_4xE=P6Ft8ZqfiWA@mail.gmail.com>
In-Reply-To: 
 <CAAE-9WFa+3qv3V9zE0kyWuhdbPjNEJPW8F_4xE=P6Ft8ZqfiWA@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 5/16/13 7:52 PM, Cuong Hoang wrote:
> The standby host will be disk-based so it
> will be less vulnerable to power loss.

If it can keep up with replay from the faster master, that sounds like a 
decent backup.  Make sure you setup all write caches very carefully on 
that system, because it's going to be your best hope to come back up 
quickly after a real crash.

Any vendor that pushes Samsung 840 drives for database use should be 
ashamed of themselves.  Those drives are turning into the new 
incarnation of what we saw with the Intel X25-E/X-25-M:  they're very 
popular, but any system built with them will corrupt itself on the first 
failure.   I expect to see a new spike in people needing data recovery 
help after losing their Samsung 840 based servers start soon.

> I forgot to mention that we'll set up Wal-e
> <https://github.com/wal-e/wal-e> to ship base backups and WALs to Amazon
> S3 continuous as another safety measure. Again, the lost of a few WALs
> would not be a big issue for us.

That's a useful plan.  Just make sure you ship new base backups fairly 
often.  If you have to fall back to that copy of the data, you'll need 
to replay anything that's happened since the last base backup happened. 
  That can easily result in a week of downtime if you're only shipping 
backups once per month, for example.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com


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