From: Royce Ausburn <royce.ml@inomial.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Craig Ringer <craig@postnewspapers.com.au>
Cc: Dan Birken <birken@gmail.com>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: Which RAID Controllers to pick/avoid?
Date: Sun, 6 Feb 2011 20:39:29 +1100
Message-ID: <743F3467-AFBC-4788-BBE9-0F896FD3405F@inomial.com> (raw)
In-Reply-To: <AANLkTikaNw=gSE8M6ry_MGRaYtdREBrS9xkVOpsFE+UF@mail.gmail.com>
References: <AANLkTimyRh1ieWxpCo1ht2D1fkmL+Ca_8ABBEw6yN2WR@mail.gmail.com>
<4D4A0C41.9020203@postnewspapers.com.au>
<AANLkTikaNw=gSE8M6ry_MGRaYtdREBrS9xkVOpsFE+UF@mail.gmail.com>
> On Wed, Feb 2, 2011 at 7:00 PM, Craig Ringer
> <craig@postnewspapers.com.au> wrote:
>> Whatever RAID controller you get, make sure you have a battery backup
>> unit (BBU) installed so you can safely enable write-back caching.
>> Without that, you might as well use software RAID - it'll generally be
>> faster (and cheaper) than HW RAID w/o a BBU.
>
> Recently we had to pull our RAID controllers and go to plain SAS
> cards. While random access dropped a bit, sequential throughput
> skyrocketed, saturating the 4 lane cable we use. 4x300Gb/s =
> 1200Gb/s or right around 1G of data a second off the array. VERY
> impressive.
This is really surprising. Software raid generally outperform hardware raid without BBU? Why is that? My company uses hardware raid quite a bit without BBU and have never thought to compare with software raid =/
Thanks!
--Royce
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To: pgsql-performance@postgresql.org
Cc: royce.ml@inomial.com, scott.marlowe@gmail.com, craig@postnewspapers.com.au, birken@gmail.com
Subject: Re: Which RAID Controllers to pick/avoid?
In-Reply-To: <743F3467-AFBC-4788-BBE9-0F896FD3405F@inomial.com>
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