Re: Miserable Disks

Optimal for single session? Maybe. Isn't this roughly what RAID-2 was supposed to do?
Of course, even then, it's really only optimal if the platters all spin and the heads all move
synchronously, isn't it?

I was under the impression that this is why RAID-2 is rarely implemented. (Normally,
I'd say "never implemented", but on this list, I just *know* somebody would correct me...)

I don't know, really. Probably for single-session applications, especially those doing huge
sequential I/O, you'd do quite nicely with just two or three of those "Stinking Huge (TM)"
ATA disks that make us shudder whenever our PHBs mention them.

;-)

Sadly, I've never bothered to benchmark this configuration, but I *am* pretty confident that
it will be far less-than-optimal for most concurrency levels much greater than 1...

On 5/26/06, Jared Still <jkstill_at_gmail.com> wrote:
>
> Comments inline.
>
>
> On 5/25/06, Mark Brinsmead <pythianbrinsmead_at_gmail.com> wrote:
>
> >
> > (*) Make your RAID stripe width really narrow (like maybe 128 or 512
> > bytes) and then
> > make your database blocks large (like 8KB or 16KB) and do lots of
> > multi-block I/O,
> > so that every I/O is assured to engage every physical drive. (Kiss
> > concurrency goodbye
> > and watch your RIOPs numbers plummet)
> >
>
> Seems like somthing like this might be optimal for single session.
> Benchmarks? ;)
>
>
>
>

-- 
Cheers,
-- Mark Brinsmead
   Staff DBA,
   The Pythian Group
   http://www.pythian.com/blogs

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