Re: Cron management...
- From: "Mladen Gogala" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "mgogala@xxxxxxxxx" for DMARC)
- To: oracle-l@xxxxxxxxxxxxx
- Date: Wed, 22 Apr 2015 18:38:58 -0400
On 04/22/2015 11:06 AM, Hans Forbrich wrote:
Issue here is the definition of BackUp. Unfortunately, I have run
across too many people who believe the RMAN executable actually does
the work of backing up the database. My post was to allow access
official references on the process.
As for central 'back up', the referenced doc mentions Oracle Secure
Backup, which is also a centralized mechanism similar in nature to
other commercial products. From that perspective, it is useful to
look at Oracle's implementation of what you describe, and that is
available at
http://docs.oracle.com/cd/E16926_01/doc.121/e16564/osb_rman_backup.htm#OBADM187
Hans, how does rman work? What happens when you do "allocate channel c0
device type SBT"? Several things happen:
* oracle process is allocated.
* MML library is mapped into the rman address space
* sbtinit routine is executed to initialize the MML side of the channel.
After that, when a "backup" command is issued, Oracle process reads the
database and delivers the data to the channel, possibly using
Oracle*Net. The channel then pumps the data toward the backup software.
That's the nature of the beast. The "rman" executable is a client,
similar to sqlplus, which executes the internal functions, built into
the Oracle executable itself and delivers the data to the destination
using the channels. If the channels are defined using MML library
("device type SBT"), then the sbtwrite and sbtwrite2 routines are used
to send the data to the backup software, be it NB, Avamar, Simpana or
something else.
In other words, if there is a centralized node used to backup all the
database by establishing remote connection to the database and opening
channel toward backup software, that node is a critical point of failure.
--
Mladen Gogala
Oracle DBA
http://mgogala.freehostia.com
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