vxfs os buffering cache

[perdida]

Hello

How can i modify a filesystem so it uses database buffer cache rather than OS buffer cache?

[A. Clay Stephenson]

If you have OnlineJFS, use these vxfs mount options:

mincache=direct,convosync=direct,nodatainlog,delaylog

Man mount_vxfs for details.

[Pete Randall]

Use the raw device, for example /dev/vg01/rlvol1, rather than /dev/vg01/lvol1.


Pete

[Sandman!]

Use the raw device as opposed to the block device for storing database files. And if this is Oracle DB then the database buffer cache is inside your SGA.

~hope it helps

[James R. Ferguson]

Hi:

Mount your VxFS filesystem with:

# mincache=direct,convosync=direct

You need OnlineJFS for this to work, but you *should* have that for a multitude of reasons.

Regards!

...JRF...

[perdida]

Thanks for your quick reply, i have online jfs and the database filesystems are mounted as:
vxfs delaylog,largefiles 0 2

what are the correct steps to modify parameters to:
vxfsdelaylog,nodatainlog,largefiles,mincache=direct,convosync=direct 0 2

??

[A. Clay Stephenson · Accepted solution]

Shutdown the database. Umount the applicable filesystems.

e.g.
umount /oradata/ora1
umount /oradata/ora2

Edit /etc/fstab to include your new mount options.

mount /oradata/ora1
mount /oradata/ora2

Restart the database.

[perdida]

Thanks for your help!