Re: shared disks in domU

["Steven M. Bellovin" <smb%cs.columbia.edu@localhost>]

On Tue, 8 Sep 2009 12:24:33 +0400
Victor Gamov <vitspec%gmail.com@localhost> wrote:

> Hi All!
> 
> Can anybody explain me how I can create shared RW virtual disk in two
> or more domU?
> 
> I use NetBSD-5.0.1 dom0 and some FreeBSD as domU.  Then I add
> someting like 'file:/VM/fbsd-disk-ports,ioemu:hdc,w'
> 
> at my HVM domU configs for both domU. I create this "disk" and mount
> it and domU-1 and domU-2
> But domU-2 can not see changes made by domU-1
> If I umount and mount disk in domU-2 again then I see changes at
> domU-2
> 
> Any suggestion for shared RW disk for two or more domU?
> 
> 
What you're doing won't work, and will likely corrupt the file
system and/or panic one or both of the machines.  There is no
intermachine locking on resources like the superblock, the inode list,
or even shared blocks on a given file.

The only way I know to do what you want is to use something like NFS.


                --Steve Bellovin, http://www.cs.columbia.edu/~smb