Re: linux readahead setting?

[erik.tews@gmx.net (Erik Tews)]

On Wed, Nov 14, 2001 at 12:26:20PM -0800, Mike Fedyk wrote:
> On Tue, Nov 13, 2001 at 10:01:39PM +0100, Erik Tews wrote:
> > Thanks, for all the answers via pm, but I would like to explain a litte
> > bit more what I am looking for. I got this filesystem on lvm, and I want
> > my harddisk if there a several processes accessing the disk-image to go
> > to the position of process one, read 256k of data, go to the position of
> > process two, read 256k of data, go again to the position of the nex
> > process, read 256k of data and so one to minimize movement of the
> > harddisk-readhead.
> 
> At which level do you want the read ahead?
> 
> If you read ahead at the block level, you may not get data for the file you
> want because of fragmentation.  This is especially true with long running
> Reiser file systems.

I think fragmentation will be no problem, because this filesystem
contains only one file.

Readahead should be done on filesystem or block-level. Not on disklevel.
I can tune that with lvm, but I was not sure if a bigger readahead-value
is that what I want.