Re: 2 questions re RAID

On Fri, Jun 17, 2011 at 11:02 AM, Scott Ribe
<scott_ribe(at)elevated-dev(dot)com> wrote:
> No responses to my earlier post, I'm assuming because OS X experience is rather thin in this group ;-) So a couple of more specific questions:
>
> 1) Is my impression correct that given a choice between Areca & Highpoint, it's a no-brainer to go with Areca?

Generally, yes, but the model of the card is more important than the
maker. I.e. an Areca 1880 or 1680 is a fantastic performer. But the
older 1120 series aren't gonna set the world on fire or anything.

Pluses for the Arecas I've used:
Out Of Band monitoring. Heck, I've updated the firmware on them from
1000 miles away.
fast in RAID-10. Lots of HW controllers (I'm looking at you, LSI)
perform poorly with layered RAID.
They all use the same simple standard battery backed unit, unlike some
manufacturers that glue them onto the DIMM so you have to buy a new
memory module to replace your BBU (again, I'm looking at you LSI)
Great UI via the web and / or the BIOS. Again, some other RAID setup
utils are not so nice (and again, I'm looking at you, LSI)

> 2) I understand why RAID 5 is not generally recommended for good db performance. But if the database is not huge (10-20GB), and the server has enough RAM to keep most all of the db cached, and the RAID uses (battery-backed) write-back cache, is it sill really an issue?

The problem with RAID-5 is crappy write performance. Being big or
small won't change that. Plus if the db is small why use RAID-5?