Re: Which RAID Controllers to pick/avoid?

> 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
useshardware raid quite a bit without BBU and have never thought to compare with software raid =/ 

Thanks!

--Royce