----- Original Message -----
Sent: Wednesday, July 16, 2003 11:39
AM
Subject: RE: RMAN & SQL
Backtrack
I
don't have any experience with SQL*Backtrack and I do have some
experience
with RMAN. Here are my
comments:
a)
RMAN is reliable. Once you write the backup scripts, they are executed by
operations
and there no surprises. In order
to rely on those scripts, one needs to test them,
especially
the recovery
part.
b)
RMAN needs a 3rd party backup software to run. Things like OmniBackup,
Tivoli, Legato or
SyncSort can be rather
expensive. RMAN doesn't write to tapes itself. RMAN delegates
a
backup software contacted
through the routines from libobk.so (or libobk.dll or libobk.sl)
to
do its writing. To get the
"libobk.so" from you backup software vendor of choice, you generally
have to write a check. That
means that RMAN is NOT free.
c)
Before version 9, RMAN was arcane and hard to learn. Thanks to Robert
Freeman, it is no
longer so. You can learn how to
configure and use RMAN and you can find a decent book
to learn RMAN from. It's not
very hard and it's fairly logical. One reading of the books suffices
for a good general
understanding.
d)
Quality of the software: RMAN leaves a lot to be desired. Its biggest
drawback is the fact that
it doesn't do any coordination
with the underlying backup catalog. In other words, you can
happily
declare backup obsolete in RMAN
and Legato will not know anything about it and vice
versa.
You can even delete backup in
Legato and reuse the tape while RMAN knows nothing about
it.
On the other hand, RMAN,
in contrast to all other methods, does not put tablespaces into
the
backup mode, thus
generating floods of redo archives. RMAN doesn't backup data blocks that
have never been used
("behind the watermark blocks"), which is great if you have a fresh
new
datafile which was added
to the tablespace just in case something might run out of
space.
e) Personnel. Despite the certification
process, it is not always easy to find a trained
personnel
which knows how to use it
and how to recover the database. I consider the ability to
recover
the database a basis for
someone to call himself/herself a DBA. You would be surprised
how
many people which claim
that title do not know how to recover the database. Even smaller number
knows how to use
RMAN.
f) I would suggest Jared Still, Cary
Millsap, Rachel Carmichael, Jonathan Lewis, Wolfgang Breitling,
Steve Adams, Gaja V., Arup
Nanda, Kirti Deshpande and Anjo Kolk to start the Oracle
List certification
process. I would trust
that one more then the OCP. I apologize to anyone who
I might have forgotten.
Mladen Gogala
Oracle DBA
Phone:(203)
459-6855
Email:[EMAIL PROTECTED]
We have been
using SQL Backtrack for backup and recovery for about 6 years
now. We are being pressured to start using RMAN because it is
free. Makes sense but I am wondering about reliability, complexity,
learning curve, etc...
Has anyone had
experience with both products or anyone new to RMAN that can give me an
idea of what to expect?
Thanks!
Ron
If you are not the intended recipient of this
e-mail message, any use, distribution or copying of the message is
prohibited. Please let me know immediately by return e-mail if you have
received this message by mistake, then delete the e-mail message. Thank
you.
