Re: [Xen-users] Sharing filesystems between VMs.

[Daniel Hulme <dh286@xxxxxxxxx>]

> This was a theory I had; I tried exporting the filesystem r/w from 
> xm-manager and r/o from the other vms, but until I changed it to r/w 
> across the board from all machines, the vms refused to boot at all - 
> fsck would hang the bootup complaining of filesystem inconsistencies.
You should export it read-only to everything. If xm-manager mounts it
read-write, the filesystem will be marked as dirty. When another domain
tries to mount it, it notices the dirty flag and fsck's it. Fsck, of
course, fails because the device is read-only. If you really need
xm-manager to be able to write to it, you could try putting whichever
mount option it is that turns off fsck'ing dirty fses in each domain's
/etc/fstab, but when xm-manager writes to the fs they will probably
break heavily.

Also, to query your config file from the other post:

>>>
# This makes the disk device depend on the vmid - assuming
# that devices sda7, sda8 etc. exist. The device is exported
# to all domains as sda1.
# All domains get sda6 read-only (to use for /usr, see below).
disk = ['file:/export/vm/vmm-root,sda1,w',
        'file:/export/vm/vmm-swap,sda2,w',
        'file:/export/vm/vm-code,sda3,w',
        'file:/export/vm/vm-usrlocal,sda4,w'
       ]
<<<

The comment mentions sda6-8, but these are not configured. This means
that the thing below,

>>>
# Sets runlevel 4 and the device for /usr.
extra = "4 VMID=%d usr=/dev/sda6" % vmid
<<<

probably won't do what you expect it to do. If you want all your domains
to have r/w access to the same device, you're going to have to use a
networked filesystem.

-- 
Stop the infinite loop, I want to get off!     http://surreal.istic.org/
Paraphernalia/Never hides your broken bones,/ And I don't know why you'd
want to try:/ It's plain to see you're on your own.        -- Paul Simon
  The documentation that can be written is not the true documentation.

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