Re: Placing Datafiles in a Striped environment

Hi

I have done similar recently on a 3 terabyte database in the UK, running on sun E4500 and A5200 arrays. We used Veritas volume manager and veritas file system. We created "manual" stripes on the disks, and plexes and volumes and then created file systems in those volumes and then allocated the tablesspaces to the relevant file systems. We used the command line tools vxadm, vxsd, vxvol ( i might have some of these wrong as i dint have a sun box in front of me as i write this. When using the command line tools rather than the GUI, you can specify cylinder numbers for the sub disks to occupy, hence you can locate files where you want on disk.

I went to great length to analyse the existing database ER diagram, table and index usage, the PL/SQL code for what tables and indexes were used in the same peices of SQL and PL/SQL and what the business use of the applications and batch processes were, so that we could seperate data to seperate physical disks for performance.

I also analysed what is HOT and what is cold. Hot tables and indexes where placed on the center of the disks, for lower latency and less head movement. the read only data and less accessed data was placed oin the edge of the disks and those tables were changed so that the rows read stayed in the LRU, cannot remember the keyword off the top of my head.

Using these techniques and others resulted in the overnight batch being reduced from 9-18 hours to 2.5 hours and it being consistant.

I have since used the same techniques on Sun ODS to place files where i want on disk.

hope this helps

cheers

Pete Finnigan
www.pentest-limited.com

In article <6cf185c9.0108292203.7e743a5f_at_posting.google.com>, Christian Lang <clang_at_mediaprint.at> writes
>Hi,
>in a lot of Articels about Striping there was spoken about to placing
>frequently accessed Datafiles on the outside half of the Disk.
>Well, how can I do this. How can I put Datafiles to the outside?
>Are Files wich are created at first located at the outer edge?
>
>thanks
>Chris

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Pete Finnigan
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