From: Scott Carey <scott@richrelevance.com>
To: Andy <angelflow@yahoo.com>, Merlin Moncure <mmoncure@gmail.com>
CC: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>,
	Greg Smith <greg@2ndquadrant.com>
Date: Wed, 6 Apr 2011 17:20:21 -0700
Subject: Re: Intel SSDs that may not suck
Thread-Topic: [PERFORM] Intel SSDs that may not suck
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Message-ID: <C9C25083.2EB4E%scott@richrelevance.com>
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On 4/6/11 2:11 PM, "Andy" <angelflow@yahoo.com> wrote:

>
>--- On Wed, 4/6/11, Scott Carey <scott@richrelevance.com> wrote:
>
>
>> I could care less about the 'fast' sandforce drives.
>> They fail at a high
>> rate and the performance improvement is BECAUSE they are
>> using a large,
>> volatile write cache.
>
>The G1 and G2 Intel MLC also use volatile write cache, just like most
>SandForce drives do.

1. People are complaining that the Intel G3's aren't as fast as the
SandForce drives (they are faster than the 1st gen SandForce, but not the
yet-to-be-released ones like Vertex 3).  From a database perspective, this
is complete BS.

2. 256K versus 64MB write cache.   Power + time to flush a cache matters.

3. None of the performance benchmarks of drives are comparing the
performance with the cache _disabled_ which is required when not power
safe.  If the SandForce drives are still that much faster with it
disabled, I'd be shocked.  Disabling a 256K write cache will affect
performance less than disabling a 64MB one.