Re: Hardware related question: 3ware 9500S

On Wed, 2006-04-12 at 13:53, Ted Byers wrote:
> ----- Original Message -----
> From: "Scott Marlowe" <smarlowe(at)g2switchworks(dot)com>
> >
> > There have been NUMEROUS discussions of RAID-5 versus RAID 1+0 in the
> > perform group in the last year or two. Short version:
> >
> Interesting.

SNIP

> This question of data security is becoming of increasing importance to me
> professionally since I will soon have to advise the company I'm working with
> regarding how best to secure the data managed by the applications I'm
> developing for them. I will need overall guidelines to produce a design
> that makes it virtually impossible for them to lose even on field in one
> record. The data is both sensitive and vital. Fortunately, I have a few
> months before we need to commit to anything. Also, fortunately, with one
> exception, the applications rely on a data feed that comes in once a day
> after normal working hours, so I won't have to worry about writes to the DB
> other than what my script does to load the datafeed into the DB. All other
> access is read only. This should make it easier to produce a strategy to
> protect the data from any kind of technology failure (software or hardware).
> Cost is a factor, but reliability is much much more important!

When you say reliability, I'm not sure your definition is my
definition. Is is that the database MUST be up during business hours,
even if the updates that happen during the day can't go through? Or
even if those updates get lost and have to be re-entered that's OK, as
long as the data entered by the batch file at night is available for
business processes.

There are a lot of ways to set this up, and each tool in the tool box
has its advantages and disadvantages. PITR, Slony Replication, pgpool,
pgcluster, mammoth replicator, bizgress, bizgress MPP...

I'd guess that the data entered during the day is the most important.
If this is so, you could set up slony replication on those tables to a
backup machine so that should the primary suffer catastrophic failure
you still have the inputs.

RAID is great, but it's no replacement for replication and / or point in
time recovery. More an augment.