Re: Intel SSDs that may not suck

On 4/6/11 4:03 PM, "gnuoytr(at)rcn(dot)com" <gnuoytr(at)rcn(dot)com> wrote:

>Not for user data, only controller data.
>

False. I used to think so, but there is volatile write cache for user
data -- its on the 256K chip SRAM not the DRAM though.

Simple power failure tests demonstrate that you lose data with these
drives unless you disable the cache. Disabling the cache roughly drops
write performance by a factor of 3 to 4 on G1 drives and significantly
hurts wear-leveling and longevity (I haven't tried G2's).

>
>
>---- Original message ----
>>Date: Wed, 6 Apr 2011 14:11:10 -0700 (PDT)
>>From: pgsql-performance-owner(at)postgresql(dot)org (on behalf of Andy
>><angelflow(at)yahoo(dot)com>)
>>Subject: Re: [PERFORM] Intel SSDs that may not suck
>>To: Merlin Moncure <mmoncure(at)gmail(dot)com>,Scott Carey
>><scott(at)richrelevance(dot)com>
>>Cc: "pgsql-performance(at)postgresql(dot)org"
>><pgsql-performance(at)postgresql(dot)org>,Greg Smith <greg(at)2ndquadrant(dot)com>
>>
>>
>>--- On Wed, 4/6/11, Scott Carey <scott(at)richrelevance(dot)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.
>>
>>--
>>Sent via pgsql-performance mailing list
>>(pgsql-performance(at)postgresql(dot)org)
>>To make changes to your subscription:
>>http://www.postgresql.org/mailpref/pgsql-performance
>
>--
>Sent via pgsql-performance mailing list (pgsql-performance(at)postgresql(dot)org)
>To make changes to your subscription:
>http://www.postgresql.org/mailpref/pgsql-performance