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Date: Wed, 1 Apr 2009 10:54:58 -0600
Message-ID: <dcc563d10904010954u582600a9t721fd1a2050a802f@mail.gmail.com>
Subject: Re: Raid 10 chunksize
From: Scott Marlowe <scott.marlowe@gmail.com>
To: Stef Telford <stef@ummon.com>
Cc: Greg Smith <gsmith@gregsmith.com>, Mark Kirkwood <markir@paradise.net.nz>,
	Scott Carey <scott@richrelevance.com>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
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On Wed, Apr 1, 2009 at 10:48 AM, Stef Telford <stef@ummon.com> wrote:
> Scott Marlowe wrote:
>> On Wed, Apr 1, 2009 at 10:15 AM, Stef Telford <stef@ummon.com> wrote:
>>
>>> =A0 =A0 I do agree that the benefit is probably from write-caching, but=
 I
>>> think that this is a 'win' as long as you have a UPS or BBU adaptor,
>>> and really, in a prod environment, not having a UPS is .. well. Crazy ?
>>>
>>
>> You do know that UPSes can fail, right? =A0En masse sometimes even.
>>
> Hello Scott,
> =A0 =A0Well, the only time the UPS has failed in my memory, was during th=
e
> great Eastern Seaboard power outage of 2003. Lots of fond memories
> running around Toronto with a gas can looking for oil for generator
> power. This said though, anything could happen, the co-lo could be taken
> out by a meteor and then sync on or off makes no difference.

Meteor strike is far less likely than a power surge taking out a UPS.
I saw a whole data center go black when a power conditioner blew out,
taking out the other three power conditioners, both industrial UPSes
and the switch for the diesel generator.  And I have friends who have
seen the same type of thing before as well.  The data is the most
expensive part of any server.