lkml.org 
[lkml]   [1999]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: cachefs module for linux?
On Thu, 10 Jun 1999, August Hörandl wrote:

> Date: Thu, 10 Jun 1999 22:41:09 +0200
> From: August Hörandl <hoerandl@elina.htlw1.ac.at>
> To: linux-kernel@vger.rutgers.edu, Jeff Garzik <jgarzik@pobox.com>
> Subject: Re: cachefs module for linux?
>
>
> There is a filesystem cache for NFS -but i am not sure if it is still useable.

Is not only for nfs but isofs, smbfs an so

> It is mentioned in the HOWTO at
> http://cuiwww.unige.ch/info/pc/remote-boot/howto-4.html#ss4.4
> and it worked with (early) 2.0 kernels; it consists of an executable
> - no source > :-(

I've asked for sources. no response yet

> and a kernel patch

But doesn't work on 2.2.X kernels :(

Their idea is simple:

a) Starting on an empty directory do a readdir() on it and makes symlinks on
every entry to the real file
b) If open regular file is made the symlink is removed and replaced with the
whole file. If the file already exists just use cached copy. No consistency
check are done over the original and cached files.
c) If opendir is requested, directory is created in the cache and cachefs
daemon performs a) on the newly created directory
d) Only cache copies are performed on directories and regular files. Symlinks
sockets, special files and so are redirected to the real file
e) when cache space is next to go out, cachefs daemon performs an unlink of
files cached ( not directories ) using a First-in-Fisrt-out algorithm. This
is the major problem: the entire cachefs is stopped during the cleanning
process ( what about a cache clean thread... a really big error )
f) Access, creation, and modification times are not consistent between cached
and original files. Lack of lock control, so we must ensure that original
files won't change and are mounted readonly (just as /usr or /opt directory)

Seems not to be very difficult patch the provided patch and create a GPL'd
source available cachefs daemon.... but not sure if the limitations on this
package make it good for starting job

Ideas?

Juan Antonio \|||/
/ _ _ \
\ o o /
=========================o00o===U===o00o======================================
Juan Antonio Martínez Universidad Politécnica de Madrid
email: jantonio@dit.upm.es E.T.S.I Telecomunicación
http://www.dit.upm.es/~jantonio Ciudad Universitaria s/n
Tel: 34-1-5495700 ext 328 Centro de Cálculo
Fax: 34-1-3367333 Madrid, Spain
==============================================================================
God Bless the pesimists... because their backups will work


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:52    [W:0.039 / U:0.720 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site