Re: Files or RAW-Devices ?

Wachs Rene <Rene.Wachs_at_ezv.admin.ch> wrote:

>Hello
 

>This summer our DEC Alpha 4000 will be replaced by a DEC 8xxxx. Today we have a 20
>GB-DB with mainly 2 large-tabs (6.5 GB-Tab with 12 mio. rows, 3.5 GB-Tab with 7
>mio. rows). Performance is satisfactory, but sometimes multiuser behaviour is
>really bad. Nobody can explain that - neither Digital nor Oracle.
 

>DEC says : on the new DEC-Box don't make Files ! Make raw-Devices ! This will
>increase performance and improve the multiuser behaviour.
 

>My questions :
 

>- is this true ? Advantages of raw-devices against files ?
>- which conditions have to be done for raw-devices ?
>- raw-devices pitfalls ?
>- practical experiences ?
 

>Thanks very much.
 

>R. Wachs

If you have ordered an 8xxx with 4GB or more of memory, you will be able to use VLM (Very large memory). This will allow you to have a very large SGA. You may also consider using BOB (Big Oracle Blocks - up to 32k) even if you do not have 4GB. However, you should experiment with your application and Oracle Block size. Sometimes the large blocks will actually hurt performance in a multiuser environment.

You may also want to look at using Digital' Logical Storage Manager to help with the administration of the disks.

Good luck,
John T. Joyal
Sr. Client/Server Consultant
Digital Equipment Corp. Received on Tue Apr 16 1996 - 00:00:00 CEST