On Wednesday 13 February 2008 07:11, David Bolt wrote:
On Wed, 13 Feb 2008, Carlos E. R. wrote:-
The Wednesday 2008-02-13 at 13:51 +0200, Dirk Moolman wrote:
Sorry, let me explain.
We are using Oracle. Oracle uses filesystems to create datafiles in, for example it will create files like:
/oradata01/system01.dbf /oradata02/users01.dbf
Is that mandatory? Can it not access a mass-storage device directly?
Now if /oradata02 (a new filesystem I created) points to the device /dev/sda, instead of /dev/sda1 (a partition on sda), will this be a problem ?
As far as I know, which isn't that much, there should be no problem.
There isn't. Reiserfs, ext2/3 and XFS all support file systems that use the entire device, not just a partition. While I haven't tried it, JFS may also support it as well.
Why wouldn't it work? The I/O model is identical whether addressing a slice / partition or the whole disk. Are there file systems that access multiple partitions? Using a separate one for a journal, maybe?
It is also possible to write a single file to a device, without filesystem (raw). I understand some databases did/do that. Being a entire device there is no problem with partition limits and overwriting another partition space, and it is supposed to be faster.
Well, it's not going to have the file system driver overhead, but some method of figuring out what part of the raw space has the data you want means that some form of file system is going to need to be implemented. In which case, you either implement your own, or use one of the already provided ones.
Well, some DBMSs do in fact manage their space from a uniform "file," which may be a device or a conventional file. Such DBMSs will probably perform better when they use a device directly. But if the DBMS uses multiple files, as MySQL does, e.g., then this is not an option. I'm a lightweight when it comes to RDBMS, but I thought Oracle could use disks directly, avoiding file-system overhead.
Regards, David Bolt
Randall Schulz -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org