From: A.M. <agentm@themactionfaction.com>
To: pgsql-performance@postgresql.org
Subject: Re: Making the most of memory?
Date: Wed, 23 Jan 2008 15:40:28 -0500
Message-ID: <B39482D3-C321-4334-99CA-3AF299DAD2CF@themactionfaction.com> (raw)
In-Reply-To: <47979C15.3040406@burntmail.com>
References: <4796BE84.9030803@centriccrm.com>
<dcc563d10801222120q78e390dbj2b884eca729c2975@mail.gmail.com>
<B30794E6-CD2A-43C1-B431-E24B56FBFB1D@concursive.com>
<dcc563d10801231044p1dba892r9b8bf1269395f068@mail.gmail.com>
<47979C15.3040406@burntmail.com>
On Jan 23, 2008, at 2:57 PM, Guy Rouillier wrote:
> Scott Marlowe wrote:
>> I assume you're talking about solid state drives? They have their
>> uses, but for most use cases, having plenty of RAM in your server
>> will
>> be a better way to spend your money. For certain high throughput,
>> relatively small databases (i.e. transactional work) the SSD can be
>> quite useful.
>
> Unless somebody has changes some physics recently, I'm not
> understanding the recent discussions of SSD in the general press.
> Flash has a limited number of writes before it becomes unreliable.
> On good quality consumer grade, that's about 300,000 writes, while
> on industrial grade it's about 10 times that. That's fine for mp3
> players and cameras; even professional photographers probably won't
> rewrite the same spot on a flash card that many times in a
> lifetime. But for database applications, 300,000 writes is
> trivial. 3 million will go a lot longer, but in non-archival
> applications, I imagine even that mark won't take but a year or two
> to surpass.
Please let outdated numbers rest in peace.
http://www.storagesearch.com/ssdmyths-endurance.html
Conclusion:
"With current technologies write endurance is not a factor you should
be worrying about when deploying flash SSDs for server acceleration
applications - even in a university or other analytics intensive
environment. "
That said, postgresql is likely making assumptions about non-volatile
storage that will need to be shattered once SSDs become more widely
deployed. Perhaps SSDs will replace RAID BBUs and then the HDs
themselves?
Cheers,
M
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Subject: Re: Making the most of memory?
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