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Responses : About Older Backups -- was Re : RMAN-NetBackup without an RMAN Catalog

From: Hemant K Chitale <>
Date: Fri, 15 Oct 2004 23:09:04 +0800
Message-Id: <>

Responding to some of the responses :

  1. RMAN is a recovery tool. I would expect to use RMAN to recover my database from a valid backup. Let's say your data was flat files and backed-up using "tar" or "cpio", 5 / 10 / 15 years ago. Can you restore it ? YES. Let's say your data was MS Word DOC or XLS Files of versions 5 years ago. Can you open those files with newer versions ? Most probably Yes. What's the catch with Oracle RMAN Versions then ? Why does Oracle have to make life difficult.
  2. Legal / Audit requirements can specify that I must be able to restore my data as of 5 or 11 years ago. Now, a well designed database may either
    1. Keep ALL data available in the current database -- such that I do not need to restore data {and without impacting performance}, provided that total volume growth isn't very large OR
    2. Implement Archive and Purge routines A poorly implemented database might just have the Application Administrator deleting data [in the course of 5 years, the Application might pass through multiple hands with successive owners not understanding the initial Legal/Audit requirements about data retention OR even the first Administrator might have not done his homework properly] {Substitute Developer / Designer / Data Owner / Dept Manager / IT Manager for "Application Administrator"} When the application was first implemented did the designers consider Retention/Archive/Purge/Remerge requirements ? Supposing that initially it was designed for 1 years data. Two years later, on a stable system, Legal requirements now state that this data must be retained for 5 or 11 years. Well, we've already lost the first year's data. And we have a stable system which was NOT designed to retain 11 years data online and also doesn't have Archive/Purge/Remerge routines. Tom's "properly designed database that can produce reports of what the database looked like 5 years ago " isn't always What You Get. Where do you go from here ? Ensure that you have monthly / quarterly / yearly backups which are, from this day forward, retained for 11 years.
  3. With Archive and Purge routines, the data *might* be transferred to flat files and burnt on CDs, it *might* be copied out as Oracle Exports and then backed up to tape. Either way, there must be a routine to restore and "re-merge" the data. How many systems have actually tested and implemented "restore and re-merge" well ?
  4. The argument that when you upgrade a database you delete the Oracle_Home isnt' convincing. If your Legal requirements say that you must be able to restore data, well you better ensure that you have that same version of the RDBMS and Application as well. Why do you think we backup the Root, /etc/passwd, /usr, ORACLE_BASE and Applications Software as well with the Database in Daily/Weekly/Monthly/Yearly backups ? Similarly with documentation on the software. [I do have a couple of 7.0 CDs and some 7.3.4 ORACLE_HOMEs on disk, other than those on tape] Because we know that we will need the same versions back. However, HW compatibility is the problem. Whether newer HW supports restoring [from tape] and reading [opening the database and running the application] the data is a concern. Also, whether the tapes are readable. So some companies do invest in "refreshing" tapes . My organisation had begun a project to migrate data from older tapes to DLT-IVs a year ago [that we had hardware issues converting the data is an "add-on" story !]
  5. Who says that I must frequently be upgrading my RDBMS version ? What significant benefit do I get trying to upgrade a mature database with a well-entrenched application ? You may call this heresy but frequently upgrading RDBMS versions isn't really justified. How frequently do I change to a new home with more rooms and better wallpaper ? Yes, newer applications go on new RDBMS versions.

Hemant K Chitale

Received on Fri Oct 15 2004 - 10:06:50 CDT

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