Re: kernel's hard drive cache

From: Rik van Riel (
Date: Fri Jun 02 2000 - 05:36:45 EST

On Sat, 3 Jun 2000, david wrote:

> i need to turn the kernel's hard drive READ / WRITE cache
> off on /dev/sdc

No you don't.

> i have to computers shearing the same scsi drive

So you will have to either mount the disk on only one
of the computers, or use a filesystem that's actually
designed to handle this situation (eg. GFS).

Ext2 and the other filesystems are not designed to
handle the case where the filesystem is mounted by
more than one computer at the same time. Even if it
were theoretically possible to share the fs by simply
turning off the caches (it isn't), that would still
result in unacceptable performance (caching is an
integral part of the design of why such an fs works well).

> how do i do this

Dont ;)

> and how do i add / remove scsi hard drives whitout rebooting the
> kernel

Read drivers/scsi/scsi.c and grep for

However, don't even think about doing this
unless your hardware supports hot-plugging!
Computer hardware is usually too expensive
to waste by doing "neat tricks" like this ;)



The Internet is not a network of computers. It is a network
of people. That is its real strength.

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