Re: To use RAW devices or not to use RAW devices.

Infortunatelly, Oracle don't encoureges the use of raw-devices, but with databases that work like Oracle work, the use of raw-devices is a must over the 'cocked files'. I have a litle experience with raw-devices, Oracle7 and Oracle8. But the capabilities of the operating system may be determinat. I have used an AIX 4.2.1, witch admit an extend of logical volumes, even while in use. The problem becames at backup time, where you cannot use tar or cpio to backup the raw-devices, in that case you must use dd. But with Oracle8 there is a good tool to make backups, even while the database is online: rman.
After that, you can create your tablespaces with 'AUTOEXTEND ON' witch don't need to create an other raw-device to expand one tablespace. To do this all you need is extend your logical volume (raw-device) and let the tablespace expand by them self. With versions of Oracle prior 7.2 (I supose) the 'AUTOEXTEND ON' does not exist witch make the use of raw-devices tedious.
After all, you have many advantages of using raw-devices, like speed, writes without operating system buffers, full use of the space of the raw-device... Conclusion: I always recomend the use of raw-devices, unless there is an incomplete aknowlege to control them at operating system level by the DB Admin.

If you want, askme for help, but don't make use of 'cocked files'...

I'm very sory about my poor english...
Good luck... (since I know you want parallel servers...)

Greg C. wrote:

> Hi out there.
>
> I am working as the DBA on a new OLTP application. I need some help with
> deciding whether we should use RAW devices. This is a 7X24 mission
> critical app, running on some flavor of UNIX, using Oracle8. We anticipate
> a very high volume of transactions.
>
> How can I determine if RAW devices are the answer to improving performance?
> Are there any other paths I should consider before jumping to RAW devices?
>
> Thank you for your help.
Received on Mon Sep 14 1998 - 16:54:23 CDT