Woops, I missed the initial message on this thread. There is no way with
XFS - or almost all filesystems to share a disk between multiple machines
in parallel. Yes, the Linux XFS is on disk compatible with Irix XFS, but
that just means you can mount the disk on one OR the other, not both at
once. Remember filesystems keep a lot of state in memory for speed, unless
the machines cooperate on the cached state you will corrupt your disk very
quickly (a read write mount on one machine and readonly on a second does not
work either by the way).
GFS is one filesystem which is capable of this - it is a complete filesystem,
not a layer which sits on top of another filesystem. It does cache coherency
by locking regions of the disk using a semaphore device (can be a software
device). GFS was initially developed on Irix, but I am pretty sure the latest
stuff is linux only - they also just removed it from under the GPL.
Another filesystem - which is available for Irix, but not Linux yet is CXFS,
this is a layer on top of XFS which does coherency and allows direct disk
access for file data. This will also not be GPLed and will cost money.
Your only other options are things like NFS, AFS etc.
> You need some mechanism to ensure mutual exclusion amongst the two machines,
> or else they will trash each other's data.
> There's a piece of software called GFS (http://www.sistina.com/gfs). I
> haven't tried it out, but it promises:
> The Global File System (GFS) is a shared disk cluster file system for Linux.
> GFS supports journaling and recovery from client failures. GFS cluster nodes
> physically share the same storage by means of Fibre Channel or shared SCSI
> devices. The file system appears to be local on each node and GFS
> synchronizes file access across the cluster. GFS is fully symmetric, that
> is, all nodes are equal and there is no server which may be a bottleneck or
> single point of failure. GFS uses read and write caching while maintaining
> full UNIX file system semantics.
> I'm not sure if GFS can work on top of XFS, or if it's a replacement for it.
> I also don't know if it'll run on IRIX. There are probably other commercial
> applications that'll do what you want, but they'd be pretty expensive..
> >I envision to make a filesystem, such that when a file is created
> >on either one system, it is visible directly on the other opposite
> >system.... Your FAQ indicate that it is possible to bring over XFS disks
> >from IRIX environment to the Linux environment, so,