Re: Hot backups vs RMAN, the rebuttal

I think your list of reasons for using RMAN is incomplete.

The database backup window may need to be shrunk not because the database is so big, but because there are a lot of systems to backup, and they use a lot of time and tape.

RMAN backs up blocks, hot backup backs up files.

Also, finding and retrieving the correct files for restoration is rather tricky when using a tape library. It can be somewhat error prone. A recovery at odd hours doesn't help much.

When you have an automated repository that can be told 'restore database', and it knows the file names to request and makes that request to the tape management system, restores are simplified.

SQL Backtrack was good for that, and now RMAN.

Our tape library is rather small, and I'm still thankful that I don't have to browse it for database files to do a restore.

At a previous employer, we used a couple of StorageTek silos: you don't really want to browse that to get all the correct files for a database. Try it when you have several hundred files.

Dave, it seems that you do work for clients scattered all around, hot backups probably works best for you.

Yes, RMAN adds some complexity. It also adds some power and efficiency.

Just test those recoveries. :)

Jared

On Tuesday 04 February 2003 09:59, Dave Morgan wrote:
> Hi All,
> I followed the recent RMAN discussion with some amusement.
> I get alot of my work rescuing sites that are using RMAN yet do not
> understand it. RF, your book is invaluable for this, thank you.
>
> First:
> no matter what method you use to backup
> TEST YOUR RECOVERY method.
>
> We don't need no stinking backups, we need recoveries :-)
>
> When to use RMAN:
> Your database is so big you cannot meet your
> backup window.
> Your database is so busy the system cannot
> handle the redo log generation
>
> Other than that, why do you need the complexities?
> Why do you accept the additional dependencies?
> Why do you accept the uncertainties?
>
> Steve, I hate to say it but backup and recovery is and
> should be boring!
>
> Rebuttals to other reasons:
>
> From TG: RMAN checks for corruption in archivelogs
> By the time I am writing archive logs to tape
> it is too late. The instance could be in trouble already.
> Archive log multiplexing (since 8.??) is the only guard
> against this.
> From RF: What if you don't understand the script?
> So the poor DBA has to read some man pages?
>
> At http://www.1001111.com I have posted a simple shell (bourne)
> script with environment file that does dynamic hot backups to disk
> and has been tested on Oracle versions 6 through 9 and on Solaris,
> Linux, AIX, SGI and HP. I have heard from another that she
> had it running under CGWIN on Windoze.
>
> Advantages:
> deploy in 5 minutes
> integration with Veritas, Legato and other backup managers
> is a one line change
> use of tar, cpio or ufsdump is a one line change
> use of bzip, compress, gzip is a one line change
> it's simple, reliable and works just about anywhere
> backs up up all init.ora files, all network.ora files
> creates and backs up a ASCII control file
> backs up all binary control files
> cloning from the backup is trivial
> easily modifiable
>
> Disadvantages
> raw tape handling has been removed as most of the
> complexity in tape backups for Oracle is dealing with
> the tape drive.
> you should understand the script before you run it
> but then you should understand RMAN before you use it too
>
> Along the backup script I have posted two monitoring/tuning scripts.
> As a contractor I often cannot install anything in the SYS schema.
> This scripts create no objects in the database at all. Everything is
> done with inline views and anonymous PL/SQL blocks.
>
> I will be posting scripts in the future. The majority will be
> in bourne shell (run anywhere is important) and will deal with
> fulfilling Oracle's needs in the OS. I have no desire to
> duplicate what is already on the web but I have noticed there is
> a shortage of OS level maintenace scripts.
>
> vi and sqlplus are my tools, until ......
>
> 4 AM MST, it's London Calling (apologies to the Clash)
> Dave our db server crashed it's available again but we
> have a corrupted /usr/bin, a couple other minor file
> systems are missing and Oracle is complaining about a
> control file missing
>
> Easy, one line change in init.ora
> with what? /usr/bin/vi :-)
>
> My first experience with ed.....
> I tolerated vi before, I love it now :-)

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Author: Jared Still
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