topic Re: deactivate the cache for ext3 in Operating System - Linux

deactivate the cache for ext3

Tonatiuh — Tue, 06 Sep 2005 20:58:47 GMT

Red Hat Enterprise Linux 4.0

Ext3 filesystems have a proper cache that acts at operation system level. This is bad when using Oracle on that filesystems.

How can I deactivate the cache of the operating system?

(example: In HP-UX is just a kernel parameter)

Re: deactivate the cache for ext3

Ivan Ferreira — Wed, 07 Sep 2005 00:11:11 GMT

I think that in Linux, there is no parameter at kernel or mount level to disable de cache of the filesystem.

You can use raw devices, or at least, disable the "access time" timestamp update (noatime).

Re: deactivate the cache for ext3

Vitaly Karasik_1 — Wed, 07 Sep 2005 03:36:15 GMT

There are several relevant articles :

http://www.linuxjournal.com/article/8539 - Optimizing Oracle 10g on Linux: Non-RAC ASM vs. LVM

-http://www.oracle.com/technology/tech/linux/pdf/Linux-FS-Performance-Comparison.pdf
Linux FS performance comparison

Re: deactivate the cache for ext3

Gopi Sekar — Wed, 07 Sep 2005 06:47:03 GMT

I am not sure whether you are talking about journaling option parameters. If you want to optimize on journal parameters then take a look at 'tune2fs' command.

Regards,
Gopi

Re: deactivate the cache for ext3

dirk dierickx — Thu, 08 Sep 2005 00:59:06 GMT

there is no such thing in linux, you should not want to run a filesystem without cache to begin with.
access to devices without caching is provided through raw devices, as long as the program knows how to use them.

Re: deactivate the cache for ext3

Erez Kirson — Tue, 28 Feb 2006 15:54:51 GMT

hey,

maybe you ment "noreservation"
try mounting your DB with this option
mount -o noreservation /mount

This is new with RHEL4 and 2.6 kernel.

it intends to improve file system layout,
not always good with DB.

hope it helps

E