Re: Any performance issues for hot backups ??

In article <3397D5DA.7A4A_at_ats.nld.alcatel.nl>, ven_at_ats.nld.alcatel.nl says...
> I am looking into the possibilities Oracle can give me
> to do 'hot backups'. From a developers point of view I don't
> have to do anything, except require that the database is started
> in the ARCHIVELOG mode. (at least that is what I read so far,
> if I am wrong in this assumption, please let me know).
>
> I am pretty sure that when I write the above as a conclusion
> I will immediately be getting responses (from within my company)
> saying that this solution is not workable because of performance issues.
> Therefor I am asking this group for 'field' experiences. Are there
> any reports or does anyone have experience that indicates that the
> performance of the Oracle database degrades (significantly) or
> hardly affects it when running in archivelog mode ?

Ok, well tell your users who think they are so smart that "Yes, there is some performance degradation." And there is also more performance degradation while the system is unavailable for cold/offline backups. So, you know have your spectrum from min to max.

The thing to do is NOT to put all of your tablespace in backup mode at the same time and perform online backups during periods of low activity around your peak OLTP/BATCH schedules. There is/may be additional performance hits taken while your backups are running from additional I/O (I'd like the users to be able to notice this one) and from additional rollback needed while tablespaces are in backup mode. But, like I said, divide and conquer your online backups and your users won't notice.

In addition, while your database is in ARCHIVELOG mode, you DO NOT HAVE TO backup all of your datafiles every night. Split your tablespaces up and backup different files over different days. For instance, on Monday, do TBLS 1-50, on TUESDAY do TBLS 51-100, etc., etc. This reduces the amount of time backing up. This may or may not meet your MTR strategies though, but work on what is best for your environment. -- neil

-- 
Neil Greene			Senior System Engineer / Oracle DBA	
MCI Systemhouse, Inc. 		<mailto:ngreene_at_laoc.SHL.com>

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