Re: Backup trends (2): HOT or COLD

On 9 Apr 2004 14:29:28 -0400, JEDIDIAH <jedi_at_nomad.mishnet> wrote:

> On 2004-04-03, Howard J. Rogers <hjr_at_dizwell.com> wrote:
[snip]

>>
>> So yes, it has lots of nice features. But those are merely incidental
>> to the
>> real reason why you should use RMAN in preference to O/S scripts:
>> performance. RMAN doesn't cause the database to generate 20 or 30 times
>> the
>> amount of redo per transaction that O/S hot backups do. RMAN doesn't
>> hammer
>
> Certainly a valid point.
>
>> one data file to death before moving on to another, but instead
>> multiplexes
>> across many datafiles, little bits being taken from each one in turn.
>> RMAN
>
> This is a just a simple coding and configuration issue.

The "cp" command takes an argument that specifies 'the first X bytes of a file', does it? Or 'the next Y bytes after that'?

Didn't think so.

In which case, no "simple coding" on your part is going to resolve the issue.

RMAN is NOT doing a cp. That's the point.

> If you take our
> korn coding as seriously as the rest of your DBA duties, this should
> never be a problem.
>
>> parallelises in a way no O/S script never could. And you can throttle
>> the
>> I/O rate up or down for RMAN to minimise the impact on the production
>> database or to maximise the speed at which the backup is done.
>
> Any of this can be crudely estimated using less complicated tools.

I'm not talking about estimating I/O rates. I'm talking about *setting* an I/O rate so that the backup operation does not hog hard disk resources to the exclusion of performance by ongoing regular users. Does the "cp" command take an I/O rate argument?

It's pretty sad if you think RMAN in 9i is "complicated".

How complicated is "backup database;"??

HJR

-- 
-------------------------------------------
Dizwell Informatics: http://www.dizwell.com
  -A mine of useful Oracle information-
          -Windows Laptop Rac-
    -Oracle Installations on Linux-
===========================================