Shared disks

[Richard Rogers]

What you are trying to do won't work. You'd have to mount both of
them read only. Your read only machine's disk caches never get
invalidated by the changes made on the read/write machine, so
you get the behavior you describe.

What you need is a parallel or distributed file system like
PVFS http://parlweb.parl.clemson.edu/pvfs/
or GFS http://www.sistina.com/

Sadly, GFS has gone commercial. There's an OpenGFS project
http://www.opengfs.org/ but I'm not sure how far along they are.

 - Richard


Jon Hittner wrote:

> Hi,
> Im not sure if what Im trying to do is possible under linux and if so, I
> thought that beowulf might be a posible solution.
>
> I just got a Hitachi 9200 Fibre disk array, and I hooked it up to two
> of my linux servers.  I created a raid set, set it up, and I can mount it
> from both systems fine.  What I want to do is mount the disk rw on one
> system and ro on the other. So the Second system can process data that
> the first one collects.  NFS is much too slow for our use.
>
> What is happening, is that the only way I can see changes I make on the
> other system, is to umount and then remount the ro volume on the second
> system. Until I do that, new files never show up, and deleted ones never
> disapear.  After I remount, then I can access all the files with no
> problem.    I have tried several filesystems (reiserfs,ext2,ext3) and I see
> the same problem.
>
> Am I missing a mount option or something?  Is this even possible? Is there
> anyting in Beowulf that would help?
>
> Thanks,
> Jon
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