Matthew wrote:
On Sat, 1 Mar 2008, Craig James wrote:
Right, I do understand that, but reliability is not a top priority in this system. The database will be replicated, and can be reproduced from the raw data.

So what you're saying is:

1. Reliability is not important.
2. There's zero write traffic once the database is set up.

Well, I actually didn't say either of those things, but I appreciate the 
feedback.  RAID 0 is an interesting suggestion, but given our constraints, it's 
not an option.  Reliability is important, but not as important as, say, a 
banking system.

And as far as zero write traffic, I don't know where that came from.  It's a 
"hitlist" based system, where complex search results are saved for the user in 
tables, and the write traffic can be quite high.

If this is true, then RAID-0 is the way to go. I think Greg's options are good. Either:

2 discs RAID 1: OS
6 discs RAID 0: database + WAL

which is what we're using here (except with more discs), or:

8 discs RAID 10: everything

Right now, an 8-disk RAID 10 is looking like the best choice.  The Dell Perc 6i 
has configurations that include a battery-backed cache, so performance should 
be quite good.

However, if reliability *really* isn't an issue, and you can accept reinstalling the system if you lose a disc, then there's a third option:

8 discs RAID 0: Everything

I imagine the MTBF on a system like this would be < 1 year, which is out of the 
question, even with a backup system that can take over.  A failure completely 
wipes the system, OS and everything, so you're guaranteed that once or twice a 
year, you have to rebuild your system from the ground up.  I'd rather spend that 
time at the beach!

Craig

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