Re: Direct IO In RH 3.0

From: Frank van Bortel <fvanbortel_at_netscape.net>
Date: Mon, 01 Mar 2004 21:59:45 +0100
Message-ID: <c2084u$vnh$1@news3.tilbu1.nb.home.nl>

Mladen Gogala wrote:

> On Sun, 29 Feb 2004 16:28:05 +0100, Frank van Bortel wrote:
>
>

>>Lost in abbreviations here: JFS stands for Journalled File System, iirc.
>>ext3 is a JFS, so you are saying ext3 does not support DIO, as it is 
>>JFS, which supports DIO.
>>Does not make sense to me...
>>
>>I thought DIO was kernel 2.6 (maybe backported to 2.4x?)
>>
>>Please explain

>
>
> JFS is IBM's file system, from AIX. Direct I/O is a low level I/O
> which is not very well supported and is usually ignored by many
> file systems (XFS reports an error). Ext2 does support direct I/O,
> but ext3 has had significant problems with it. The latest versions
> of ReiserFS no longer report an error woth it, while JFS works.
> Veritas charges significant amount of money for "Quick I/O" option,
> which is, essentially, ability to do direct I/O. JFS for linux
> is described at: http://www-124.ibm.com/jfs
> Direct I/O is an ability of the filesystem, and doesn't have much to
> do with kernel. I don't know about ext3 on 2.6 kernels, there may have
> been some improvements.
>

Nice link. Thanks.

The site does talk about JFS being included in the kernel (2.4, even)

-- 

Regards,
Frank van Bortel

Received on Mon Mar 01 2004 - 14:59:45 CST