Message-ID: <51414409.6090505@catalyst.net.nz>
Date: Thu, 14 Mar 2013 16:29:13 +1300
From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
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To: pgsql-performance@postgresql.org
Subject: Re: New server setup
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On 14/03/13 09:16, David Boreham wrote:
> On 3/13/2013 1:23 PM, Steve Crawford wrote:
>>
>> What concerns me more than wear is this:
>>
>> InfoWorld Article:
>> http://www.infoworld.com/t/solid-state-drives/test-your-ssds-or-risk-massive-data-loss-researchers-warn-213715
>>
>>
>> Referenced research paper:
>> https://www.usenix.org/conference/fast13/understanding-robustness-ssds-under-power-fault
>>
>>
>> Kind of messes with the "D" in ACID.
>
> It is somewhat surprising to discover that many SSD products are not
> durable under sudden power loss (what where they thinking!?, and ...why
> doesn't anyone care??).
>
> However, there is a set of SSD types known to be designed to address
> power loss events that have been tested by contributors to this list.
> Use only those devices and you won't see this problem. SSDs do have a
> wear-out mechanism but wear can be monitored and devices replaced in
> advance of failure. In practice longevity is such that most machines
> will be in the dumpster long before the SSD wears out. We've had
> machines running with several hundred wps constantly for 18 months using
> Intel 710 drives and the wear level SMART value is still zero.
>
> In addition, like any electronics module (CPU, memory, NIC), an SSD can
> fail so you do need to arrange for valuable data to be replicated.
> As with old school disk drives, firmware bugs are a concern so you might
> want to consider what would happen if all the drives of a particular
> type all decided to quit working at the same second in time (I've only
> seen this happen myself with magnetic drives, but in theory it could
> happen with SSD).
>
>

Just going through this now with a vendor. They initially assured us 
that the drives had "end to end protection" so we did not need to worry. 
I had to post stripdown pictures from Intel's s3700, showing obvious 
capacitors attached to the board before I was taken seriously and 
actually meaningful specifications were revealed. So now I'm demanding 
to know:

- chipset (and version)
- original manufacturer (for re-badged ones)
- power off protection *explicitly* mentioned
- show me the circuit board (and where are the capacitors)

Seems like you gotta push 'em!

Cheers

Mark


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