Re: Restore Oracle 8i database

From: Mark Bole <makbo_at_pacbell.net>
Date: Sat, 18 Jun 2005 00:23:48 GMT
Message-ID: <oQJse.4094$Pa5.1543@newssvr21.news.prodigy.com>

DA Morgan wrote:
> Randy Harris wrote:
>

[...]

>>
>> As far as what is and isn't a "backup"...  One could probably make a
>> rational argument that a photograph of the server is a backup of sorts.

>
>
> Except that you can not restore from it other than as an all-or-nothing.
> I know Oracle uses the phrase but it is truly no substitute for an real
> backup.

Your definition of "backup" needs expanding. Sure, most of the emphasis is on protecting a running database in real time, but there are plenty of backup and restore scenarios that don't fit that definition.

The EXP/IMP process is not monolithic at all, it is extremely flexible in terms of choosing what to backup and restore -- schemas, table structure, indexes, constraints, data rows, grants, statistics, and so on. (The documentation for Data Pump indicates a slight shift away from this degree of flexibility, but I haven't used it enought to say for sure).

For example, given an entity and its dependents (a parent row in one table and all its related, cascaded child rows in a set of other tables), it is fairly straightforward to script a backup/restore process for just that set of rows.

I used this when faced once with a series of ad hoc data "cleanups" -- as each customer's data became ready for cleansing (repeated for many customers over a period of many calendar months) the pre-cleanup records (and ONLY those records) were completely backed up using logical backup techniques (EXP). Even years later, regardless of hardware and software upgrades, or schema changes, it would be possible, upon request of the customer, to restore this logical backup within a few seconds. You can't say that about physical backups, and even the Flash Recovery Area in 10g would make it challenging to go back for years. The logical backup has the added benefit of having the timestamp "built in", in other words you don't have to try to guess the exact date/time or SCN of the data you want, it's already implicit in the backup itself.

As for the "photograph of the server is a backup of sorts": I know one former manager who did, in fact, have a simple, two-pronged disaster recovery strategy: digital photos of the server equipment racks, and a consistent export generated every two weeks and stored on tape off-site at a commercial service. Beyond that, everything about backup and recovery was left entirely up to my discretion. And yes, I did make physical backups... ;-)

-Mark Bole Received on Fri Jun 17 2005 - 19:23:48 CDT