| From: | Royce Ausburn <royce(dot)ml(at)inomial(dot)com> |
|---|---|
| To: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
| Cc: | Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, Dan Birken <birken(at)gmail(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Which RAID Controllers to pick/avoid? |
| Date: | 2011-02-06 09:39:29 |
| Message-ID: | 743F3467-AFBC-4788-BBE9-0F896FD3405F@inomial.com |
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| Lists: | pgsql-performance |
> On Wed, Feb 2, 2011 at 7:00 PM, Craig Ringer
> <craig(at)postnewspapers(dot)com(dot)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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