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Home -> Community -> Usenet -> c.d.o.server -> Re: Some questions from database newbie
Tom,
What IS your backup / recovery strategy?
This question is answered by a statement such as this:
We cannot afford to lose more than 1 [minute, hour, day, week, ...]
of our database inserts, updates, deletes.
Then you devise tactics to achieve that goal.
For example, if it is OK to lose a week's worth of processing, weekly
cold backups is good enough.
Daily cold backups limit your loss to a day's worth.
When you can only lose 1 hour or 1 minute, you probably cannot do cold backups that often. You will need to run your database in ARCHIVELOG mode. This allows you to use the logs to roll forward after restoring crashed files. Only the in-flight transactions (not yet committed) would be lost.
ARCHIVELOG mode also enables hot backups, in case you do not have enough time for cold backups. You can roll forward after restoring either a hot or cold backup.
Important note: export is NOT a backup. If you import some tables from
a prior export, there is no roll-forward possible even if you are in ARCHIVELOG
mode. So you are back to the point where you lose all work on those tables
since the last export. And, unless you take special precautions, there
is no guarantee of consistency between multiple tables in an export. The
export / import utilities have many uses, but must be used carefully in
a backup / recovery situation.
Thomas M. Payerle wrote:
A while ago our database person left us and in the interim until-----------------------------------------------
a new person is hired I got stuck with looking after the databases on top
of everything else. After several weeks of crash course in databases,
SQL, Oracle, etc (eg like having a real life test of my predecessor's
backup strategies)
Received on Sat Oct 17 1998 - 18:23:20 CDTTom Payerle
Dept of Physics payerle@physics.umd.edu
University of Maryland (301) 405-6973
College Park, MD 20742-4111 Fax: (301) 314-9525
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