Re: Relate raw disks to Oracle database?

Colin F. Melville wrote:
> Can anyone tell me a simple method for relating raw disks to
> specific Oracle databases?
>
>
> System is a K200 running HP-UX 10.10 & Oracle 7.1.x.
> Colin,
This can be achieved by the following convoluted means with HP-UX 10.10:-

Use SAM's Logical Volume Manager (LVM). Find documentation on this within the HP-UX man pages. (see appendix below. Effectively, LVM enables soft-formatting or creation of partitions on the disk. These partitions can then be extended or further partitions added (at the end of the disk) without re-installation of the disk (contents).

Create Volume Groups to represent disks and Logical Volumes to represent partitions (user data spaces on the disks).

1. Optionally (recommended) Define One Volume Group per physical disk. This enables you to manage the partition-drive assignments that the OS may otherwise perform for you.
2. Create a logical volume (soft-partition) for each Database space (Chunk) to be used within Oracle. Consider the location of these chunks relative to other usage of the disk (contention) and the physical location within the cylinders (average seek time).

In creating each logical volume, choose
a) Custom logical volume names such as
ora1_<funca>
ora2_<funcb>
This will facilitate later identification of the usage of the logical volumes within SAM.

b) a mount point /tmp/xxx_ora1, /tmp/xxx_ora2, ... These will enable HP-UX to build filesystems on the logical volumes.
Note: Due to deficiencies within HP-UX 10.x, it is impossible to create user data volumes without first creating a filesystem on them, and then removing it.

3. Once the volumes have been created and mounted, go to SAM's Filesystem via and remove each filesystem that was just created in step 2. This will leave "unused" logical volumes that contain no active filesystems, but can be used by Oracle.

4. Ensure your system administrators understand what has happened and do not try to "re-use" the logical volumes which appear in SAM's Logical Volumes view as "unused".

5. Consider building symbolic link references to the volumes to facilitate disaster recovery and load balancing exercises in the future. If Oracle references a symbolic (soft) link to the real device driver (/dev/vgxx/oraxx_funcxx), then the device can be re-assigned without tearing down and rebuilding the entire DBMS environment.

I use a directory per DBMS instance, in which links refer to the real devices. With INFORMIX OnLine, for example I define a DBMS Instance using ONCONFIG=onconfig.inst_name and
INFORMIXSERVER=inst_name and then /inf/<inst_name> contains symbolic links to the appropriate devices, which are defined as DBSpaces within INFORMIX using these names (/inf/<inst_name>/xxxx).

Appendix
Finding HP-UX man pages
Try "man -k lvm" to see all related man pages, alternatively see the overview "man 7 lvm".

If you get an error "...whatis missing", then run "catman -w &" to build the indexes, but beware that this dumps core under HP-UX 10.10 without patches. You will need a patch from HP for this (I don't have the number right now).
-Jez Received on Mon Dec 09 1996 - 00:00:00 CET