Re: Raw partitions vs. file system

S V <sv1_at_mindspring.com> wrote in article <01bce47d$a431bfe0$c85c0c26_at_sfinance3>...

> > What about backups? To backup raw devices in Unix (when you don't have
> > any special backup software) you need to use dd - and I won't rely on
 dd
> > backups for a database.
>
> what's wrong with "dd" ???

To my knowledge there are no verification with dd and it is very slow - especially if you have to back GB's every month. And having to run dd backups for over 24 hours gets to be a problem in a production environment.

> I would rather rely on dd which is absolutely
> reliable piece of soft furniture, tested over generations than on some
> third-party tools full of bugs.

We're using a 3rd party X-based tool. Works great! - and it outperforms dd by far.

> well, this is simply NOT TRUE.
> All it takes
> to move a datafile from /dev/rlv01 to /dev/rlv02
> is
> ALTER TABLESPACE AAA OFFLINE;
> dd if=/dev/rlv01 of=/dev/rlv02 bs=4k skip=1 seek=1
> ALTER TABLESPACE AAA RENAME DATAFILE '/dev/rlv01' TO '/dev/rlv02';
> ALTER TABLESPACE AAA ONLINE;
Ah ok - I retract that it's not impossible. :-) But what you fail to mention that you must make sure that the raw slices should be the same size or else you'll waste space. With file systems you have more flexibility. You can have multiple variable size datafiles per file system. With raw devices it is a single fixed size datafile per raw slice. Shuffling data files around on file systems are much easier.

The biggest problem IMHO is that you require solid Unix skills to administer and maintain raw devices - and this is usally outside the scope of knowledge required by an Oracle DBA.

> to delete raw device it takes _at least root access to the box.
> I would never use root account for running a database.
> To delete a cooked file, it suffices to be only oracle,
> which is a step lower level of security.

Agreed, but only the DBA should have oracle access. But too often security is lax and developers have root and/or oracle access. I don't think that security should be a factor when it comes to raw vs cooked files.

regards,
Billy Received on Thu Oct 30 1997 - 00:00:00 CST