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Each of these can grow to have 1GB of differences from the master volume. You can

grow the amount of space for storing the differences using the lvextend command, e.g.:

# lvextend +100M /dev/vg/myclonedisk1

Don’t let the ‘differences volume’ ever ﬁll up otherwise LVM gets rather confused. It

may be possible to automate the growing process by using dmsetup wait to spot the

volume getting full and then issue an lvextend.

In principle, it is possible to continue writing to the volume that has been cloned (the

changes will not be visible to the clones), but we wouldn’t recommend this: have the

cloned volume as a ‘pristine’ ﬁle system install that isn’t mounted directly by any of

the virtual machines.

5.4 Using NFS Root

First, populate a root ﬁlesystem in a directory on the server machine. This can be on a

distinct physical machine, or simply run within a virtual machine on the same node.

Now conﬁgure the NFS server to export this ﬁlesystem over the network by adding a

line to /etc/exports, for instance:

/export/vm1root 1.2.3.4/24 (rw,sync,no_root_squash)

Finally, conﬁgure the domain to use NFS root. In addition to the normal variables, you

should make sure to set the following values in the domain’s conﬁguration ﬁle:

root = ’/dev/nfs’

nfs_server = ’2.3.4.5’ # substitute IP address of server

nfs_root = ’/path/to/root’ # path to root FS on the server

The domain will need network access at boot time, so either statically conﬁgure an

IP address (Using the conﬁg variables ip, netmask, gateway, hostname) or enable

DHCP ( dhcp=’dhcp’).

Note that the Linux NFS root implementation is known to have stability problems

under high load (this is not a Xen-speciﬁc problem), so this conﬁguration may not be

appropriate for critical servers.

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Belkin XM Commander Manuale Utente Pagina 30