Re: Mirroring/stripping question

"Guy Dallaire" <gd-newsgroups_at_spamex.com> wrote in message news:1xQpb.641$143.28461_at_news20.bellglobal.com...
> Say you have 8 disks in a hardware raid controller on which you want to
> place oracle datafiles. Your redo logs are duplexed on another separate
pair
> of disks. You want mirroring
>
> What is the best scenario:
>
> a) Create 4 mirrors of two disks each, and treat each mirror as separate
> devices, place indexes and data files on separate disk, juste like on a
> regular disk.

Is there no end to this madness?

Why physically separate indexes and data files?? Why????

It provides no performance benefit. And you can create separate tablespaces to get the management benefits, and still house both tablespaces on the same array.

In case you're new here, please have a butcher's at google.com for this newsgroup over the past year. You will discover a general consensus (finally!) that index/table-separation-yields-performance-benefits is just another hoary old myth from the Oracle Stables. Long since debunked and totally untrue even when being promulgated by The Corporation itself (which its latest doco now no longer does, thank God.)

By the way, I would go (a) or (c), with a preference towards (a). I'd prefer to keep SYSTEM, UNDO and TEMP away from everything else if at all possible. So if I was doing (a), it would be 4 arrays, 1 for SYSTEM, 1 for UNDO, 1 for TEMP and 1 for everything else. Regardless of whether it's an index or a table.

The only problem with that distribution is that SYSTEM rarely needs to be bigger than a couple of hundred meg. Even I, with my shares in Seagate, have a problem recommending an entire 30GB+ RAID array for SYSTEM on its own.

(c) has the advantage of utter simplicity, and such looney space wastage issues don't arise. And for the majority of databases out there, the performance worries that arise from striping everything together probably won't be an issue. Probably. Maybe.

>
> b) Create 2 stripped mirrors of 4 disks each, one for indexes, one for
> tables.
>
> c) Create 1 big stripped mirror with the 8 disks and place all datafiles
on
> it, regardless of types of segments.
>
> The RAID Array is a sun storedge 3310 with 2 controllers (512 Mb cache)
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Received on Tue Nov 04 2003 - 19:41:17 CST