Re: Incremental Backup and Change Block Tracking Questions

From: Syed Jaffar Hussain <sjaffarhussain_at_gmail.com>
Date: Fri, 22 Feb 2008 19:42:16 +0300
Message-ID: <97b7fd2f0802220842u7df09147m8026c14456d4389a@mail.gmail.com>


>
>
> 1. Have you found Incremental backups and Change Block Tracking to be
> reliable; i.e, can you reliably backup and then restore and recover?
>
> >> For dozens of our business critical databases we are doing an
> incremental/cumulative incremental backups and we have had no issues whether
> with back or recovery scenarios. Indeed we have benefited with BCT on our
> historical database (data warehouse). It drastically reduced our backup
> time.
>
> 2. What about Oracle compression during an RMAN backup? Is that reliable?
>
> >>As you knew that an RMAN (pre 10gR2) comes with NULL compression
> facility. You really need to test the binary compression and then decide. If
> binary compression works good with somebody, may not fit exatly into your
> env. I think R&D would be a good choice.
>

3. How much of a performance hit using the Change Block Tracking feature?
> What about Oracle compression?
>
> >> Oracle says that definately there is increase in the CPU usage while
> performing compressed or BCT feature. May not be very highy.
>

> 4. Do you know if any of these features are additional cost? Do you know
> if there is a view in Oracle that outlines what features come with EE and
> what features are additional cost?
>
> >> If I am not wrong, there is an additional cost involved. (please
> correct me)
>
> 5. We also have the option to do compression at the tape drive level. Is
> anybody aware of any reason that Oracle compression (during backup) would be
> better or worse than letting the tape drive do it?
>
>
>
> 6. I have read that restores of a cumulative backup a generally faster
> than restores of a differential backup. What makes cumulative faster? Is
> it simply that RMAN will just one incremental file to restore and recover
> from (plus archive logs)? If there are six differential backups to recover
> from, RMAN should be able to restore and recover the six files without DBA
> intervention. I don't see a significant time difference. Perhaps a couple
> minutes extra because it has six more files to deal with?
>
> The other fact is that cumulative backups takes more time than
> differential backups. I guess, Advanced RMAN document will be handy for more
> calarity.
>

> Thanks for your input!
>
>
>
> *Sam Bootsma*
>
> *Oracle Database Administrator*
>
> *Information** Technology Services**
> George Brown College*
>
> *Phone: 416-415-5000 x4933**
> Fax: 416-415-4836**
> E-mail: **sbootsma_at_georgebrown.ca* <sbootsma_at_georgebrown.ca>
>
>
>

-- 
Best Regards,

Syed Jaffar Hussain
Oracle ACE
8i,9i & 10g OCP DBA
RAC Certified Expert

Official Oracle RAC SIG Representative for Saudi Arabian region  (
http://www.oracleracsig.org/)
http://jaffardba.blogspot.com/
http://apex.oracle.com/pls/otn/f?p=19297:4:1579866181463918::NO:4:P4_ID:126
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Received on Fri Feb 22 2008 - 10:42:16 CST

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