Re: Redo logs - need a guru

In article <4tgh2t$84c_at_main.dscga.com>, bcoogler_at_dscga.com wrote:

> Hello Steve.
>
> To add my own 2 cents worth to Frank's comments:

[snip...]

> >Step 2. Move Redos to their own disk - and - insure that it is
> >setup for large writes - and - if archiving reads.
>
> If you can, set up your redo logs in raw logical volumes. This will
> improve I/O and allow you to take advantage of async I/O, which on HP
> is only available in raw. I have found having at least the redo logs
> in raw space really helps. But first, you will need to implement
> async I/O.

But you'll also want to mirror the redos in another disk. If you're keeping redos for critical recovery, and you have *one* disk on which non-mirrored redo logs reside, you're hosed if that disk goes bad.

You may have assumed that, but if others are looking on, it's just a gentle reminder that you want to keep two identical sets of redo logs mirrored on two different disks where applicable. (For example, some of our databases don't *have* redo logs; the database is kept in sync with a Unix filesystem for version control of software, so the only good recovery we have there is a full backup/restore of the database and the associated filesystem data. That doesn't lend itself to using redo logs.)

-- 
Tim Irvin, HP-UX Miracle Worker and Oracle Guy
Lockheed Martin Missiles and Space, Sunnyvale, California
e-mail: irvin_at_lmsc.lockheed.com    voice:  (408) 742-0440
************ all standard disclaimers apply ************