Message-ID: <d32d411b09d8e7c614772de567a94229.squirrel@sq.gransy.com>
In-Reply-To: <201108241848.061232@ms14.lnh.mail.rcn.net>
References: <4E49B0A0.2060705@2ndQuadrant.com>
	<201108241848.061232@ms14.lnh.mail.rcn.net>
Date: Wed, 24 Aug 2011 21:32:16 +0200
Subject: Re: Reports from SSD purgatory
From: "Tomas Vondra" <tv@fuzzy.cz>
To: gnuoytr@rcn.com
Cc: pgsql-performance@postgresql.org
User-Agent: SquirrelMail/1.4.21
MIME-Version: 1.0
Content-Type: text/plain;charset=utf-8
Content-Transfer-Encoding: 8bit
Importance: Normal

On 24 Srpen 2011, 20:48, gnuoytr@rcn.com wrote:

> It's worth knowing exactly what that means.  Turns out that NAND quality
> is price specific.  There's gooduns and baduns.  Is this a failure in the
> controller(s) or the NAND?

Why is that important? It's simply a failure of electronics and it has
nothing to do with the wear limits. It simply fails without prior warning
from the SMART.

> Also, given that PG is *nix centric and support for TRIM is win centric,
> having that makes a big difference in performance.

Windows specific? What do you mean? TRIM is a low-level way to tell the
drive 'this block is empty and may be used for something else' - it's just
another command sent to the drive. It has to be supported by the
filesystem, though (e.g. ext4/btrfs support it).

Tomas